
True Irradiance & The Biggest Scam in the Red Light Therapy Industry
Now we're going to talk about the best irradiance or intensity for full body red light therapy. We must emphasize up front that the terms “best intensity” or irradiance does not mean having the highest level of irradiance. Irradiance and the wavelengths used are the most important elements to look for in a bed or full body panel, and we have to get both right for red light therapy to be effective. If we use the wrong wavelengths and/or an irradiance that is either too weak or too intense, not only may we not get positive results, we may also possibly do ourselves more harm than good.
Irradiance causes some of the worst confusion in the entire red light therapy industry for two reasons. The first is the (incorrect) claim that more irradiance or more power is better. The second source of uncertainty is that we can perform irradiance measurements with any light meter, like solar power meters, which can wildly skew the irradiance measurements much higher than they really are. As we'll see, the TRUTH is that while more is NOT better, we do need a certain level of irradiance to be effective (many if not most beds are underpowered). To obtain accurate measurements of irradiance, we must use a lab-calibrated spectroradiometer which sadly VERY few companies are doing. In fact, most companies use solar power meters that can give irradiance values up to FOUR TIMES higher than what they are!! The great two-fold deception in the red light industry right now is first, pushing the notion that more irradiance is better, and second, using cheap and inaccurate solar powered meters to measure inflated irradiance values. Talk about a double whammy!
In this chapter, we will flesh out the unvarnished truth of irradiance to help everyone "see the light" and have clarity as to the best range or window of irradiance to use, along with HOW to properly measure irradiance. After we define it, we'll explore the ideal irradiance range, or "irradiance window," for improving human health and vitality to ensure we receive and enjoy all the wonderful red light benefits we saw in chapters 6-9.
Now we're going to talk about the best irradiance or intensity for full body red light therapy. We must emphasize up front that the terms “best intensity” or irradiance does not mean having the highest level of irradiance. Irradiance and the wavelengths used are the most important elements to look for in a bed or full body panel, and we have to get both right for red light therapy to be effective. If we use the wrong wavelengths and/or an irradiance that is either too weak or too intense, not only may we not get positive results, we may also possibly do ourselves more harm than good.
Irradiance causes some of the worst confusion in the entire red light therapy industry for two reasons. The first is the (incorrect) claim that more irradiance or more power is better. The second source of uncertainty is that we can perform irradiance measurements with any light meter, like solar power meters, which can wildly skew the irradiance measurements much higher than they really are. As we'll see, the TRUTH is that while more is NOT better, we do need a certain level of irradiance to be effective (many if not most beds are underpowered). To obtain accurate measurements of irradiance, we must use a lab-calibrated spectroradiometer which sadly VERY few companies are doing. In fact, most companies use solar power meters that can give irradiance values up to FOUR TIMES higher than what they are!! The great two-fold deception in the red light industry right now is first, pushing the notion that more irradiance is better, and second, using cheap and inaccurate solar powered meters to measure inflated irradiance values. Talk about a double whammy!
In this chapter, we will flesh out the unvarnished truth of irradiance to help everyone "see the light" and have clarity as to the best range or window of irradiance to use, along with HOW to properly measure irradiance. After we define it, we'll explore the ideal irradiance range, or "irradiance window," for improving human health and vitality to ensure we receive and enjoy all the wonderful red light benefits we saw in chapters 6-9.

So what exactly is Irradiance?
Recall that light is a form of electromagnetic radiation bearing properties of both waves and particles. The therapeutic value of red and near infrared light is first characterized by its wavelength (distance between two peaks) or frequency, which we explored in detail in the last chapter. Yet light is also characterized by its amplitude, intensity or energy content. Energy is quantified as joules (J) and the amount of energy delivered per unit time (s=seconds) constitutes the power of light in watts (W=J/s).
The energy content or intensity of light in red light therapy and photobiomodulation research is nearly always reported as irradiance, its power density expressed in watts per meter squared (W/m^2) or more commonly in mW/cm^2 (milliwatts per centimeter squared). A simple, useful way to understand irradiance is that it’s the brightness of a light source, which in this book means the intensity of the light from a full body red light LED panel or bed.
Dosage is the energy density, fluence or radiant exposure when we apply light to an organism reported in Joules/cm^2, which is simply the irradiance multiplied by the treatment time. Treatment time is critically important too! (more on dosage in the next chapter). For medical, research and clinical applications, we understand light in terms of these three aforementioned parameters - wavelength (nm), irradiance or power density (mW/cm2) and radiant exposure, fluence or dose (J/cm2). [1-3]
Let’s simplify these parameters a bit. Metaphorically, let’s think of red light therapy as a miracle "red pill" supplement. In this hypothetical scenario, wavelength would be the medicine or "active ingredient" in this red pill, like say vitamin D or vitamin C. Irradiance (or intensity/amount) would be how many milligrams of this active ingredient are in each pill, say 1000mg of vitamin C. Dosage or fluence would be how many pills we take at once, along with how many times per day (and week) we consume them. Let’s say we have a red light therapy bed with 660nm and 830nm wavelengths and an irradiance of 30mW/cm^2, used once a day every other day. That’s the way the three most important parameters in red light therapy (wavelength, irradiance and dosage) tie together. These are really the ONLY three physical parameters important in a full body red light bed. Everything else we hear is marketing hype (assuming the red light bed has a top and bottom with a uniform light distribution because some red light beds are open or 1/2 beds and some panels and some beds do not spread the light out evenly).
The "Big Three" Summarized: Wavelength vs Energy Content vs Dosage
1) Wavelength is the medicine or active ingredient (different wavelengths are multi-light-mins)
2) Irradiance is the milligrams of the active ingredient per pill (intensity or brightness)
3) Dosage is how many pills we take (and how often we take them) = Irradiance x Time
Recall that light is a form of electromagnetic radiation bearing properties of both waves and particles. The therapeutic value of red and near infrared light is first characterized by its wavelength (distance between two peaks) or frequency, which we explored in detail in the last chapter. Yet light is also characterized by its amplitude, intensity or energy content. Energy is quantified as joules (J) and the amount of energy delivered per unit time (s=seconds) constitutes the power of light in watts (W=J/s).
The energy content or intensity of light in red light therapy and photobiomodulation research is nearly always reported as irradiance, its power density expressed in watts per meter squared (W/m^2) or more commonly in mW/cm^2 (milliwatts per centimeter squared). A simple, useful way to understand irradiance is that it’s the brightness of a light source, which in this book means the intensity of the light from a full body red light LED panel or bed.
Dosage is the energy density, fluence or radiant exposure when we apply light to an organism reported in Joules/cm^2, which is simply the irradiance multiplied by the treatment time. Treatment time is critically important too! (more on dosage in the next chapter). For medical, research and clinical applications, we understand light in terms of these three aforementioned parameters - wavelength (nm), irradiance or power density (mW/cm2) and radiant exposure, fluence or dose (J/cm2). [1-3]
Let’s simplify these parameters a bit. Metaphorically, let’s think of red light therapy as a miracle "red pill" supplement. In this hypothetical scenario, wavelength would be the medicine or "active ingredient" in this red pill, like say vitamin D or vitamin C. Irradiance (or intensity/amount) would be how many milligrams of this active ingredient are in each pill, say 1000mg of vitamin C. Dosage or fluence would be how many pills we take at once, along with how many times per day (and week) we consume them. Let’s say we have a red light therapy bed with 660nm and 830nm wavelengths and an irradiance of 30mW/cm^2, used once a day every other day. That’s the way the three most important parameters in red light therapy (wavelength, irradiance and dosage) tie together. These are really the ONLY three physical parameters important in a full body red light bed. Everything else we hear is marketing hype (assuming the red light bed has a top and bottom with a uniform light distribution because some red light beds are open or 1/2 beds and some panels and some beds do not spread the light out evenly).
The "Big Three" Summarized: Wavelength vs Energy Content vs Dosage
1) Wavelength is the medicine or active ingredient (different wavelengths are multi-light-mins)
2) Irradiance is the milligrams of the active ingredient per pill (intensity or brightness)
3) Dosage is how many pills we take (and how often we take them) = Irradiance x Time

Irradiance - How Much is Ideal?
What is the perfect irradiance to use in a whole-body red light therapy bed or panel? While we don’t find a clear consensus on an exact value, we fortunately do encounter a range of values that have optimal therapeutic effects. To best understand this optimal window of irradiance for full body red light panels and beds, we'll check out four important pieces of evidence: 1) the sun's natural irradiance for red and near infrared; 2) research studies in photobiomodulation showing a biphasic dose response; 3) specific whole-body red light bed studies; and finally, 4) heating effects as a limiting factor. All poetic implications aside, let's first look at the marvels of nature and the sun as our guiding light.
What is the perfect irradiance to use in a whole-body red light therapy bed or panel? While we don’t find a clear consensus on an exact value, we fortunately do encounter a range of values that have optimal therapeutic effects. To best understand this optimal window of irradiance for full body red light panels and beds, we'll check out four important pieces of evidence: 1) the sun's natural irradiance for red and near infrared; 2) research studies in photobiomodulation showing a biphasic dose response; 3) specific whole-body red light bed studies; and finally, 4) heating effects as a limiting factor. All poetic implications aside, let's first look at the marvels of nature and the sun as our guiding light.

A. Nature's Guiding Light For Irradiance
“Comprehend and Copy Nature” —Viktor Schauberger
On the surface of the earth, the sun gives us between 20-40 mW/cm^2 irradiance of red and near infrared light between the proven 600nm-1100nm range, depending on the season and specific geography. As we'll see, this range or window serendipitously agrees with the ideal therapeutic window that photobiomodulation research has found to be the most effective irradiances!
The article “Infrared and Skin: Friend or Foe” (Barolet 2016) confirms this conclusion, saying, “Photobiomodulation exposure to visible and IR - A light [near infrared] which emulates the conditions of natural sunlight in wavelength, intensity, and dosage can be beneficial to the skin.” [5] The bottom line is, we cannot force our body to absorb photons faster than nature intended. If we try, we end up with counterproductive results, as research shows us [6]. We’re best advised to emulate nature whenever possible, because after all, we have co-existed and co-evolved with nature for millions of years.
“Comprehend and Copy Nature” —Viktor Schauberger
On the surface of the earth, the sun gives us between 20-40 mW/cm^2 irradiance of red and near infrared light between the proven 600nm-1100nm range, depending on the season and specific geography. As we'll see, this range or window serendipitously agrees with the ideal therapeutic window that photobiomodulation research has found to be the most effective irradiances!
The article “Infrared and Skin: Friend or Foe” (Barolet 2016) confirms this conclusion, saying, “Photobiomodulation exposure to visible and IR - A light [near infrared] which emulates the conditions of natural sunlight in wavelength, intensity, and dosage can be beneficial to the skin.” [5] The bottom line is, we cannot force our body to absorb photons faster than nature intended. If we try, we end up with counterproductive results, as research shows us [6]. We’re best advised to emulate nature whenever possible, because after all, we have co-existed and co-evolved with nature for millions of years.
In another published study by Barolet entitled "Near-Infrared Light and Skin: Why Intensity matters,” he fine tunes the irradiance recommendation to between 30-35 mW/cm^2 as a beneficial "sweet spot" that corresponds to the irradiance of the sun (for red and near infrared light). Barolet emphasizes that we want to be in the range that sunlight delivers to us. He adds that it's very clear that if we’re trying to work with intensities much higher than what sunlight delivers, we’ll have major issues because our skin is not built to handle it on a thermal level. That’s the reason we get overheated and feel deleterious health effects [7]. We think it is best to take Barolet's and Viktor Schauberger's advice to comprehend and copy nature using red light therapy devices designed to mimic the sun's natural levels, which evolution has custom tailored to be what the body needs and wants.
B. 5- 50 Rule Irradiance
Keep the Irradiance under 50 mW/cm^2 (but greater than 5 mW/cm^2)
Now that we have seen what the sun and nature provide for us, what does actual scientific research say about irradiance? The consensus in the photobiomodulation community seems to be to keep the irradiance under 50 mW/cm^2, which is true for most but not all red light therapy devices. In "Infrared and Skin: Friend or Foe," the author offers that lower irradiance <50 mW/cm^2 is less likely to induce detrimental effects. [5]
Lower irradiance (< 50 mW/cm2) is less likely to induce skin hyperthermia leading to potential deleterious effects.
To further confirm this, a paper by Huang, Sharma and Hambin reflects their conclusion that irradiances ranging from 5 to 50 mW/cm^2 are generally effective for stimulation, healing and regeneration [7]. While some of these studies casually mention 5 mW/cm^2 as a lower bound, it seems that 50 mW/cm^2 is pretty much a hard ceiling. For full body therapy, we personally feel 5mW/cm^2 is too low because it’s lower than the natural range of the sun (<20 mW/cm^2) and most of the studies using these low irradiance numbers are laser studies. Also as we'll see next, the LOWEST irradiance used in any red light bed or full body LED study was 13 mW/cm^2. Let's get more clarity on the ideal therapeutic irradiance window by looking at a comprehensive list of full-body red and near infrared LED beds and canopy clinical studies.
More Studies Showing 5-50 mW/cm^2
Hamblin, M, et al. (2018). Low-level light therapy: Photobiomodulation. Society of Photo-Optical Instrumentation Engineers (SPIE) [from pg 10]:
"Assuming that the reported parameters can be trusted, studies of beam irradiance report successful tissue repair and anti-inflammatory effects from 5–50 mW/cm2 at the target tissue depth.[25-27]"
Keep the Irradiance under 50 mW/cm^2 (but greater than 5 mW/cm^2)
Now that we have seen what the sun and nature provide for us, what does actual scientific research say about irradiance? The consensus in the photobiomodulation community seems to be to keep the irradiance under 50 mW/cm^2, which is true for most but not all red light therapy devices. In "Infrared and Skin: Friend or Foe," the author offers that lower irradiance <50 mW/cm^2 is less likely to induce detrimental effects. [5]
Lower irradiance (< 50 mW/cm2) is less likely to induce skin hyperthermia leading to potential deleterious effects.
To further confirm this, a paper by Huang, Sharma and Hambin reflects their conclusion that irradiances ranging from 5 to 50 mW/cm^2 are generally effective for stimulation, healing and regeneration [7]. While some of these studies casually mention 5 mW/cm^2 as a lower bound, it seems that 50 mW/cm^2 is pretty much a hard ceiling. For full body therapy, we personally feel 5mW/cm^2 is too low because it’s lower than the natural range of the sun (<20 mW/cm^2) and most of the studies using these low irradiance numbers are laser studies. Also as we'll see next, the LOWEST irradiance used in any red light bed or full body LED study was 13 mW/cm^2. Let's get more clarity on the ideal therapeutic irradiance window by looking at a comprehensive list of full-body red and near infrared LED beds and canopy clinical studies.
More Studies Showing 5-50 mW/cm^2
Hamblin, M, et al. (2018). Low-level light therapy: Photobiomodulation. Society of Photo-Optical Instrumentation Engineers (SPIE) [from pg 10]:
"Assuming that the reported parameters can be trusted, studies of beam irradiance report successful tissue repair and anti-inflammatory effects from 5–50 mW/cm2 at the target tissue depth.[25-27]"
Note: We can use higher irradiances, but their main value is nerve inhibition and pain relief. In terms of using it for pain relief, studies have only been done on spot applications like in lasers, NOT whole body red light LED panels or beds! All the studies with higher irradiance are done with LASERS! While higher irradiance might have a meaningful place in certain situations, it is only with LASERS and focused spot therapy, NOT full body panels and beds. [8]
*Further NOTE ON ANALGESIA*:
Analgesia is a different matter; a systematic review of laboratory studies found that higher irradiances of 300–1730 mW/cm2 are necessary to inhibit nerve conduction in C fibers and A-delta fibers. [28]
*Further NOTE ON ANALGESIA*:
Analgesia is a different matter; a systematic review of laboratory studies found that higher irradiances of 300–1730 mW/cm2 are necessary to inhibit nerve conduction in C fibers and A-delta fibers. [28]

C. Clinically Backed Irradiance Recommendations (from 10 Full Body Red Light Studies)
Looking at official studies of full body red light LED is crucial because we cannot rely on those using focused lasers or small LED pads to guide us in our search for a full body LED device. Scanning the research literature, there seems to be only ten red light therapy studies (at the time of this writing) that use a full body LED bed or canopy (most studies are with lasers or small devices). That number should shock us because numerous red light bed companies usually quote laser studies to back up their marketing, usually to justify high irradiance (> 50 mW/cm^2) or pulsing (see appendix A); both of which have no place in full body red light therapy! We should scrutinize these specific full body studies to know what irradiance and dosage they used.
To get an accurate and reliable irradiance recommendation, there is nothing more informative than actual randomized control trial studies conducted with full body red light LED beds or panels. If we take the average irradiance of these 10 studies that were successful (three showed no result), it is (rounding up) 28 mW/cm^2 - likely a good benchmark to go by as it is based on studies done with whole-body light beds that showed clinically proven results (not just lasers or small devices).
Irradiance From All Studies = (28 + 28 + 28 + 28 + 28 + 28 + 32.8 + 16.6 + 13.05 + 46.17)/10 = 27.66 mW/cm^2 Average
The lowest irradiance here is 16.6 mW/cm^2 and the highest is 46.17 mW/cm^2 and notice they are ALL below 50 mW/cm^2! It seems these studies “got the memo” of the many reasons we should not use irradiance values above 50 mW/cm^2. These irradiances from actual studies with full body red light LEDs very nicely match the ranges of both what nature provides us and also what experts AND in depth research recommends. So quite happily, let’s call this what it is - a great trifecta of confirmation as to the ideal therapeutic window of irradiances to use, agreed upon by nature, research and top experts in the field!
Note: Because we’re covering a large area of the body with great intensity, our total joules absorbed will be very high. This makes the risk of overdosing with full body panels and beds that claim high irradiance numbers greater than overdosing with smaller panels that claim high irradiance values (because the total energy of light in Joules absorbed is much greater with a bed due to its larger area Total Energy (Joules) = Area x Irradiance). This means we must be ESPECIALLY careful to use the proper irradiance and dosage.
Looking at official studies of full body red light LED is crucial because we cannot rely on those using focused lasers or small LED pads to guide us in our search for a full body LED device. Scanning the research literature, there seems to be only ten red light therapy studies (at the time of this writing) that use a full body LED bed or canopy (most studies are with lasers or small devices). That number should shock us because numerous red light bed companies usually quote laser studies to back up their marketing, usually to justify high irradiance (> 50 mW/cm^2) or pulsing (see appendix A); both of which have no place in full body red light therapy! We should scrutinize these specific full body studies to know what irradiance and dosage they used.
To get an accurate and reliable irradiance recommendation, there is nothing more informative than actual randomized control trial studies conducted with full body red light LED beds or panels. If we take the average irradiance of these 10 studies that were successful (three showed no result), it is (rounding up) 28 mW/cm^2 - likely a good benchmark to go by as it is based on studies done with whole-body light beds that showed clinically proven results (not just lasers or small devices).
Irradiance From All Studies = (28 + 28 + 28 + 28 + 28 + 28 + 32.8 + 16.6 + 13.05 + 46.17)/10 = 27.66 mW/cm^2 Average
The lowest irradiance here is 16.6 mW/cm^2 and the highest is 46.17 mW/cm^2 and notice they are ALL below 50 mW/cm^2! It seems these studies “got the memo” of the many reasons we should not use irradiance values above 50 mW/cm^2. These irradiances from actual studies with full body red light LEDs very nicely match the ranges of both what nature provides us and also what experts AND in depth research recommends. So quite happily, let’s call this what it is - a great trifecta of confirmation as to the ideal therapeutic window of irradiances to use, agreed upon by nature, research and top experts in the field!
Note: Because we’re covering a large area of the body with great intensity, our total joules absorbed will be very high. This makes the risk of overdosing with full body panels and beds that claim high irradiance numbers greater than overdosing with smaller panels that claim high irradiance values (because the total energy of light in Joules absorbed is much greater with a bed due to its larger area Total Energy (Joules) = Area x Irradiance). This means we must be ESPECIALLY careful to use the proper irradiance and dosage.

Conclusion - The Ideal Window of Irradiance
Using the above three criteria, we can get a good idea of the best irradiance window to use in red and near infrared light therapy. We want at least as much RED/IR as Nature but not more than the upper bounds of the PBM research and the whole body bed research. So while it is not definitive, a starting point is to look at the range from nature and the full body red light bed studies. Combing both gives a range from 13-46 mW/cm^2. Further refining our range we can take Barolet's advice of the 30-35mW/cm^2 sweet spot in Nature and the average, median and standard deviation of the 11 red light bed studies. Doing some basic statistics the mean or average irradiance of the 7 successful studies is 27 mW/cm^2, the median or middle number is 28 mW/cm^2, which is also the mode (most occurrences). And the sample standard deviation is 11.9 mW/cm^2. So if we use values that fall within one standard deviation 27.87mW/cm^2 +/- 11.9mW/cm^2 the ideal range from the studies would be about 16-40 mW/cm^2.
Because this is based on successful research you should make SURE the LED panel or bed ideally has at least 16 mW/cm^2 irradiance, but NO MORE than 40 mW/cm^2. This research-proven range aligns with both nature and leading experts recommendations. Based on our direct experience of using several different red light beds very extensively, we are convinced you want a bed more in the 27-35 mW/cm^2 range which is Nature's "sweet spot" that Barolet talks about. So if pressed, that would be our recommendation for an ideal irradiance window for full body red light therapy which does fall within all three criteria of Nature, research and red light bed studies. And it is also our experience if you use beds with even over 40 mW/cm^2 they start to become uncomfortably hot, further confirming directly that more is NOT better! And this leads us to one more piece of information to further confirm the upper ceiling of this range 50 mW/cm^2 which we'll look at next: heating effects.
Using the above three criteria, we can get a good idea of the best irradiance window to use in red and near infrared light therapy. We want at least as much RED/IR as Nature but not more than the upper bounds of the PBM research and the whole body bed research. So while it is not definitive, a starting point is to look at the range from nature and the full body red light bed studies. Combing both gives a range from 13-46 mW/cm^2. Further refining our range we can take Barolet's advice of the 30-35mW/cm^2 sweet spot in Nature and the average, median and standard deviation of the 11 red light bed studies. Doing some basic statistics the mean or average irradiance of the 7 successful studies is 27 mW/cm^2, the median or middle number is 28 mW/cm^2, which is also the mode (most occurrences). And the sample standard deviation is 11.9 mW/cm^2. So if we use values that fall within one standard deviation 27.87mW/cm^2 +/- 11.9mW/cm^2 the ideal range from the studies would be about 16-40 mW/cm^2.
Because this is based on successful research you should make SURE the LED panel or bed ideally has at least 16 mW/cm^2 irradiance, but NO MORE than 40 mW/cm^2. This research-proven range aligns with both nature and leading experts recommendations. Based on our direct experience of using several different red light beds very extensively, we are convinced you want a bed more in the 27-35 mW/cm^2 range which is Nature's "sweet spot" that Barolet talks about. So if pressed, that would be our recommendation for an ideal irradiance window for full body red light therapy which does fall within all three criteria of Nature, research and red light bed studies. And it is also our experience if you use beds with even over 40 mW/cm^2 they start to become uncomfortably hot, further confirming directly that more is NOT better! And this leads us to one more piece of information to further confirm the upper ceiling of this range 50 mW/cm^2 which we'll look at next: heating effects.

D. Overdosing and Heating Effects Decreases Penetration and Efficacy
There is another major reason why we do not want to use beds or full body panels with an accurately measured irradiance over 50mW/cm^2 - and that has to do with the heating up of our skin and tissue. When we have conducted tests using 40-45 mW/cm^2 irradiance in a full body bed, it noticeably starts to become uncomfortably hot after a few minutes. Thus, from a purely experiential point of view along with the backing of nature and years of research, it’s clear why 50 mW/cm^2 (measured correctly) should be a hard ceiling to irradiance and you can even make a case for 40 mW/cm^2 due to experientially feeling uncomfortably hot. The tissue heating effects from using high irradiance result in several additional problems that we will now go over. There is no escaping the fact that as we increase the irradiance, we elevate tissue heating. Some beds on the market literally make us sweat inside the bed (and encourage it), and as we'll see, this is NOT a helpful thing at all and in fact could me even deleterious to your health in the long run!
Where does the heat come from?
We generally consider LEDs more efficient and lower in heat generation than their incandescent bulb predecessors. However, they still create heat as a byproduct of electricity flowing through them. In fact, while only 20-30% of the LED power emits as light, the rest of the energy generates as heat.[17] Let's now look at five additional key reasons to keep our red light bed under 50 mW/cm^2 to minimize such heating.
1) High Irradiances Decreases Penetration Depth
The first problem with higher irradiance increasing skin and body temperature is that tissue optical properties change with temperature, such as absorption and scattering properties (due to increased thermal vibrations). As we increase irradiance beyond 50 mW/cm^2 and start heating the skin and tissue, the penetration depth of the light is LOWERED (and it is important to note that any wavelength can cause heating at high irradiances). This is exactly the opposite of what we want, which is that our red and near infrared light penetrates as deeply as possible [13]. Besides increasing absorption and scattering (which reduces penetration depth), heat also elevates our heart rate and circulation so much that it can further hinder penetration. Finally, higher skin temperature can make us sweat, a phenomenon we know from experience happens with higher irradiances especially above 50 mW/cm^2. Sweating in turn creates an additional water-based layer of reflection and absorption (like a second "skin"), further lowering penetration depth in addition to the decreased penetration from tissue heating (another double whammy).
2) Increase ROS + Biphasic Dose (Overtraining)
Not only do high irradiances cause excessive heating that lowers penetration depth, they also overstimulate the mitochondria and create way TOO MUCH reactive oxygen species (ROS). Recall from Chapter 8 that red and near infrared therapy is an exercise mimetic, which means at the cellular level its responses mimic exercise. Like exercise, we can overdo, or "overtrain," with red light therapy. At the cellular level, overtraining manifests as too much ROS or oxidative stress (free radical damage). As we also saw in Chapter 8, a little ROS helps strengthen our cells and improve antioxidants and overall cellular strength and resiliency (like exercise can also do), but an over-supply of ROS has the opposite effect. This is the basis for the biphasic dose curve we'll explore in more detail in the next chapter (heating will drastically increase the ROS production, leading to a faster biphasic dose response). For now, let’s think in terms of overexercising and overtraining our cells. Excessive irradiance creates unhealthy levels of ROS free radicals, which we saw is a main root cause inflammation! [11] Instead of healing and energizing our body, too much red-light therapy will cause an inhibitory effect and cancel out the hoped for benefits. [11] There can also be too much nitric oxide and nasty RNS (reactive nitrogen species) from overdoing red light therapy. The right amount of those is healthy, Recall from chapter 7 and 8 that both ROS and nitric oxide are "Janus faced" - a little of both is good but too much is damaging [22]. Note: Even with a powerful fan going, over-exposure to light still overstimulates the mitochondria and increases ROS, so even if we take measures to cool our body in a high irradiance bed, it will STILL create too much ROS if the irradiance and/or session time is too high! Recall photobiomodulation expert Daniel Barolet's advice: "The bottom line is you cannot force your body to absorb photons faster than nature intended."
3) Research confirms More is NOT Better
Research studies confirm that there is a range of effective irradiance values, and when we use irradiances that are too high, the results are less effective and sometimes even harmful and inhibitory. For optimal red and near infrared light benefits, most studies are carefully designed to minimize heating. This is why we rarely see high irradiance values in clinical studies. One of the main themes of this book is that we want to stick with clinical studies and research (along with nature) and not resort to "guess-ology" or marketing hype. One study states, " In general, the power densities used for PBM are lower than those needed to produce heating of tissue." [9] Another declares that large temperature increases in the tissue during PBM have been associated with less desirable outcomes. [11] Yet another study found that holding skin temperature constant at 37°C led to good results, while allowing it to heat to 45°C led to a doubling of free-radical formation and half of the antioxidant power. Both were conducted while holding the dose steady. [11] Finally, a study on wound healing stated, "As an increased wound temperature can correlate with decreased wound healing and wound bed score." [10] All this research clearly confirms that more is NOT better. Just like in our diets, moderation in all things! We need a certain amount of irradiance for it to be effective, but we do not want to go too high - especially above 50 mW/cm^2. There are ZERO full body red light bed or led panel studies that show ANY benefit of using irradiance values higher than 50 mW/cm^2 - ZERO! ZIPPO! NADA!
4) FDA Safety
The maximum safe skin temperature set by the FDA is 41 Celsius (106 degrees Fahrenheit). Anything above this will cause burns or degrading effects. [12] [13] [14] That is also the pain threshold, and typically the user will stop usage due to discomfort. Our body will start to sweat to lower skin temperature, and this sweat further reflects and absorbs light, lowering penetration depth. One red light bed company was reported to the FDA because they put the LEDs right next to the acrylic, which was causing dozens of reported burns on unsuspecting patients. Another person we talked to used a high irradiance bed and told us he had to put his hands under his tailbone because the acrylic was so hot!! OUCH! This is NOT AT ALL THE WAY IT SHOULD BE! Along with irradiance that’s way too high, other factors like the surface temperature of the acrylic are important. Important note: If the LEDs are too close to the acrylic, the heat from the LEDs can cause excessive heating to the skin even at lower irradiances. This needs to be publicized more, because some dubious companies incorrectly claim the LEDs need to be as close to the surface as possible. The truth is that what matters is near field measurements of irradiance with a lab calibrated spectroradiometer where the skin is at. (we'll revisit this appendix C "Myth vs Science").
5) Not good for the eyes
Most will agree that our eyes are much more sensitive to heat damage than the skin. So we need to be extra careful with our eyes compared to the rest of our body. Too much intensity can quickly lead to increased ROS, tissue heating, or even burning if the irradiance is too high, which sensitive eyes would feel immediately. Research confirms this. One analysis shows that the eye can only tolerate 80mW/cm^2 of IR LED less than 30 seconds! Any more would risk having lasting thermal damages. [20] Also, the IEC-62471 also states a safe limit is only 57 mW/cm^2 for less than 100 seconds! [21] If someone were to obtain a light that ACTUALLY emits >100mW/cm^2, that could be hazardous to our eyes. This may sound like fear mongering, but it’s straightforward information by regulatory agencies and research. The companies that make these high intensity claims won't tell us the truth about eye safety. With high irradiance systems, we would be forced to wear eye protection and sadly lose out on potential benefits for the eyes. Research shows that there are great potential benefits for eye health with an appropriate dose of red and near infrared light therapy (especially 660-670nm).
All of the five above-mentioned reasons (and more) are why photobiomodulation/red light therapy studies are careful to use lower intensities to ensure a non-thermal tissue response. Heating will lower penetration depth and drastically increase ROS production, leading to possible inhibitory effects and even cell damage! It can even be harmful to our eyes. So BE CAREFUL! For optimal PBM benefits, most studies are carefully designed to minimize heating. Which brings us to another highly important question: How can we minimize heating effects?
There is another major reason why we do not want to use beds or full body panels with an accurately measured irradiance over 50mW/cm^2 - and that has to do with the heating up of our skin and tissue. When we have conducted tests using 40-45 mW/cm^2 irradiance in a full body bed, it noticeably starts to become uncomfortably hot after a few minutes. Thus, from a purely experiential point of view along with the backing of nature and years of research, it’s clear why 50 mW/cm^2 (measured correctly) should be a hard ceiling to irradiance and you can even make a case for 40 mW/cm^2 due to experientially feeling uncomfortably hot. The tissue heating effects from using high irradiance result in several additional problems that we will now go over. There is no escaping the fact that as we increase the irradiance, we elevate tissue heating. Some beds on the market literally make us sweat inside the bed (and encourage it), and as we'll see, this is NOT a helpful thing at all and in fact could me even deleterious to your health in the long run!
Where does the heat come from?
We generally consider LEDs more efficient and lower in heat generation than their incandescent bulb predecessors. However, they still create heat as a byproduct of electricity flowing through them. In fact, while only 20-30% of the LED power emits as light, the rest of the energy generates as heat.[17] Let's now look at five additional key reasons to keep our red light bed under 50 mW/cm^2 to minimize such heating.
1) High Irradiances Decreases Penetration Depth
The first problem with higher irradiance increasing skin and body temperature is that tissue optical properties change with temperature, such as absorption and scattering properties (due to increased thermal vibrations). As we increase irradiance beyond 50 mW/cm^2 and start heating the skin and tissue, the penetration depth of the light is LOWERED (and it is important to note that any wavelength can cause heating at high irradiances). This is exactly the opposite of what we want, which is that our red and near infrared light penetrates as deeply as possible [13]. Besides increasing absorption and scattering (which reduces penetration depth), heat also elevates our heart rate and circulation so much that it can further hinder penetration. Finally, higher skin temperature can make us sweat, a phenomenon we know from experience happens with higher irradiances especially above 50 mW/cm^2. Sweating in turn creates an additional water-based layer of reflection and absorption (like a second "skin"), further lowering penetration depth in addition to the decreased penetration from tissue heating (another double whammy).
2) Increase ROS + Biphasic Dose (Overtraining)
Not only do high irradiances cause excessive heating that lowers penetration depth, they also overstimulate the mitochondria and create way TOO MUCH reactive oxygen species (ROS). Recall from Chapter 8 that red and near infrared therapy is an exercise mimetic, which means at the cellular level its responses mimic exercise. Like exercise, we can overdo, or "overtrain," with red light therapy. At the cellular level, overtraining manifests as too much ROS or oxidative stress (free radical damage). As we also saw in Chapter 8, a little ROS helps strengthen our cells and improve antioxidants and overall cellular strength and resiliency (like exercise can also do), but an over-supply of ROS has the opposite effect. This is the basis for the biphasic dose curve we'll explore in more detail in the next chapter (heating will drastically increase the ROS production, leading to a faster biphasic dose response). For now, let’s think in terms of overexercising and overtraining our cells. Excessive irradiance creates unhealthy levels of ROS free radicals, which we saw is a main root cause inflammation! [11] Instead of healing and energizing our body, too much red-light therapy will cause an inhibitory effect and cancel out the hoped for benefits. [11] There can also be too much nitric oxide and nasty RNS (reactive nitrogen species) from overdoing red light therapy. The right amount of those is healthy, Recall from chapter 7 and 8 that both ROS and nitric oxide are "Janus faced" - a little of both is good but too much is damaging [22]. Note: Even with a powerful fan going, over-exposure to light still overstimulates the mitochondria and increases ROS, so even if we take measures to cool our body in a high irradiance bed, it will STILL create too much ROS if the irradiance and/or session time is too high! Recall photobiomodulation expert Daniel Barolet's advice: "The bottom line is you cannot force your body to absorb photons faster than nature intended."
3) Research confirms More is NOT Better
Research studies confirm that there is a range of effective irradiance values, and when we use irradiances that are too high, the results are less effective and sometimes even harmful and inhibitory. For optimal red and near infrared light benefits, most studies are carefully designed to minimize heating. This is why we rarely see high irradiance values in clinical studies. One of the main themes of this book is that we want to stick with clinical studies and research (along with nature) and not resort to "guess-ology" or marketing hype. One study states, " In general, the power densities used for PBM are lower than those needed to produce heating of tissue." [9] Another declares that large temperature increases in the tissue during PBM have been associated with less desirable outcomes. [11] Yet another study found that holding skin temperature constant at 37°C led to good results, while allowing it to heat to 45°C led to a doubling of free-radical formation and half of the antioxidant power. Both were conducted while holding the dose steady. [11] Finally, a study on wound healing stated, "As an increased wound temperature can correlate with decreased wound healing and wound bed score." [10] All this research clearly confirms that more is NOT better. Just like in our diets, moderation in all things! We need a certain amount of irradiance for it to be effective, but we do not want to go too high - especially above 50 mW/cm^2. There are ZERO full body red light bed or led panel studies that show ANY benefit of using irradiance values higher than 50 mW/cm^2 - ZERO! ZIPPO! NADA!
4) FDA Safety
The maximum safe skin temperature set by the FDA is 41 Celsius (106 degrees Fahrenheit). Anything above this will cause burns or degrading effects. [12] [13] [14] That is also the pain threshold, and typically the user will stop usage due to discomfort. Our body will start to sweat to lower skin temperature, and this sweat further reflects and absorbs light, lowering penetration depth. One red light bed company was reported to the FDA because they put the LEDs right next to the acrylic, which was causing dozens of reported burns on unsuspecting patients. Another person we talked to used a high irradiance bed and told us he had to put his hands under his tailbone because the acrylic was so hot!! OUCH! This is NOT AT ALL THE WAY IT SHOULD BE! Along with irradiance that’s way too high, other factors like the surface temperature of the acrylic are important. Important note: If the LEDs are too close to the acrylic, the heat from the LEDs can cause excessive heating to the skin even at lower irradiances. This needs to be publicized more, because some dubious companies incorrectly claim the LEDs need to be as close to the surface as possible. The truth is that what matters is near field measurements of irradiance with a lab calibrated spectroradiometer where the skin is at. (we'll revisit this appendix C "Myth vs Science").
5) Not good for the eyes
Most will agree that our eyes are much more sensitive to heat damage than the skin. So we need to be extra careful with our eyes compared to the rest of our body. Too much intensity can quickly lead to increased ROS, tissue heating, or even burning if the irradiance is too high, which sensitive eyes would feel immediately. Research confirms this. One analysis shows that the eye can only tolerate 80mW/cm^2 of IR LED less than 30 seconds! Any more would risk having lasting thermal damages. [20] Also, the IEC-62471 also states a safe limit is only 57 mW/cm^2 for less than 100 seconds! [21] If someone were to obtain a light that ACTUALLY emits >100mW/cm^2, that could be hazardous to our eyes. This may sound like fear mongering, but it’s straightforward information by regulatory agencies and research. The companies that make these high intensity claims won't tell us the truth about eye safety. With high irradiance systems, we would be forced to wear eye protection and sadly lose out on potential benefits for the eyes. Research shows that there are great potential benefits for eye health with an appropriate dose of red and near infrared light therapy (especially 660-670nm).
All of the five above-mentioned reasons (and more) are why photobiomodulation/red light therapy studies are careful to use lower intensities to ensure a non-thermal tissue response. Heating will lower penetration depth and drastically increase ROS production, leading to possible inhibitory effects and even cell damage! It can even be harmful to our eyes. So BE CAREFUL! For optimal PBM benefits, most studies are carefully designed to minimize heating. Which brings us to another highly important question: How can we minimize heating effects?

How do we manage temperature in Full Body Red and Near Infrared Light Therapy?
So how do we handle those problematic heating effects? The most obvious way is to use a lower irradiance, ideally below 50 mW/cm^2. Meticulous research informs us that the perfect range is approximately 16-40 mW/cm^2. If you go anywhere above 50mW/cm^2, watch out! We’ll definitely start to feel the fire – or at least our body heating up a bit more than feels comfortable.
Here’s a cool tip for improving red light penetration depth: Do a cold plunge or cryotherapy session BEFORE red light. And there is good research and biophysics to support this: One group of researchers discovered a higher level of effectiveness and 27.5% better penetration of 810nm laser simply by applying cryotherapy to the skin before treatment! That’s a fancy way of saying they used ice for 20 minutes. [16] It’s all the proof we need to declare that the cooler our skin and body are, the more efficient, helpful and healing the results will be! This icy reality also has an interesting connection to solar panels that are likewise much more efficient in colder temperatures (and remember, cytochrome c oxidase porphyrins are literally little solar cells). It’s easier to absorb light in colder temperatures! So here’s a great biohack we can all enjoy: Let’s do a cold plunge, or cryotherapy session, BEFORE our red light session! Immerse, indulge, and chill out (literally!)
Having low EMF effective fans inside the bed helps cool it down. It’s best to find a red light bed that uses clean direct DC power to power the fans because adding unhealthy EMF. Sadly, most red light bed companies use the AC 60 Hz, which generally has dirty electricity piggy backing along. However, fans cannot cool our back laying in a red light bed, so high irradiances will still cause it to heat up and sweat profusely, which is our personal experience. Understanding that “too cold” is uncomfortable for most people, we can lower the room temperature to cool yet pleasant, acceptable levels. Those of us with a spa must strike a balance. The easiest solution? Steer clear of red light beds with irradiance values above 50 mW/cm^2. Here is an important takeaway from this experience: Even if we CAN cool our body, using irradiance numbers higher than 50mW/cm^2 will STILL increase ROS and oxidative stress.
Concluding Thoughts - Unethical Marketing Part 1:
When companies say their equipment has the highest intensity, what they really mean is that their beds or panels have not been studied for safety and effectiveness. We know the actual full body red light LED studies have never gone beyond 50 mW/cm^2. It's important for us to become aware of our biases. Many of us assume that if a little bit of something is good, more is even better. But let’s be real - that's not the case at all! We can hurt ourselves doing too much exercise, gain weight eating an excessive amount of nutritional food, get diarrhea from too much vitamin C, get sunburned from too much sun exposure, et al, ad nauseum!
In preventive and energy medicine, we must discipline ourselves follow where science leads us – which means NOT EVER listening to the boasts of red light companies that tout more power as their foolish unfounded marketing gimmick. Next, we'll dig into the second major scam in the red light industry - false reporting of irradiance using uncalibrated solar power meters and other varieties of uncalibrated light meters. We'll demonstrate the proper way to measure light with a singular goal in mind: That this information will grow proverbial wings and take flight to at last rid the red light industry of these RIDICULOUS LIES about irradiance and thereby anchor recommendations in the truth of trustworthy research!
So how do we handle those problematic heating effects? The most obvious way is to use a lower irradiance, ideally below 50 mW/cm^2. Meticulous research informs us that the perfect range is approximately 16-40 mW/cm^2. If you go anywhere above 50mW/cm^2, watch out! We’ll definitely start to feel the fire – or at least our body heating up a bit more than feels comfortable.
Here’s a cool tip for improving red light penetration depth: Do a cold plunge or cryotherapy session BEFORE red light. And there is good research and biophysics to support this: One group of researchers discovered a higher level of effectiveness and 27.5% better penetration of 810nm laser simply by applying cryotherapy to the skin before treatment! That’s a fancy way of saying they used ice for 20 minutes. [16] It’s all the proof we need to declare that the cooler our skin and body are, the more efficient, helpful and healing the results will be! This icy reality also has an interesting connection to solar panels that are likewise much more efficient in colder temperatures (and remember, cytochrome c oxidase porphyrins are literally little solar cells). It’s easier to absorb light in colder temperatures! So here’s a great biohack we can all enjoy: Let’s do a cold plunge, or cryotherapy session, BEFORE our red light session! Immerse, indulge, and chill out (literally!)
Having low EMF effective fans inside the bed helps cool it down. It’s best to find a red light bed that uses clean direct DC power to power the fans because adding unhealthy EMF. Sadly, most red light bed companies use the AC 60 Hz, which generally has dirty electricity piggy backing along. However, fans cannot cool our back laying in a red light bed, so high irradiances will still cause it to heat up and sweat profusely, which is our personal experience. Understanding that “too cold” is uncomfortable for most people, we can lower the room temperature to cool yet pleasant, acceptable levels. Those of us with a spa must strike a balance. The easiest solution? Steer clear of red light beds with irradiance values above 50 mW/cm^2. Here is an important takeaway from this experience: Even if we CAN cool our body, using irradiance numbers higher than 50mW/cm^2 will STILL increase ROS and oxidative stress.
Concluding Thoughts - Unethical Marketing Part 1:
When companies say their equipment has the highest intensity, what they really mean is that their beds or panels have not been studied for safety and effectiveness. We know the actual full body red light LED studies have never gone beyond 50 mW/cm^2. It's important for us to become aware of our biases. Many of us assume that if a little bit of something is good, more is even better. But let’s be real - that's not the case at all! We can hurt ourselves doing too much exercise, gain weight eating an excessive amount of nutritional food, get diarrhea from too much vitamin C, get sunburned from too much sun exposure, et al, ad nauseum!
In preventive and energy medicine, we must discipline ourselves follow where science leads us – which means NOT EVER listening to the boasts of red light companies that tout more power as their foolish unfounded marketing gimmick. Next, we'll dig into the second major scam in the red light industry - false reporting of irradiance using uncalibrated solar power meters and other varieties of uncalibrated light meters. We'll demonstrate the proper way to measure light with a singular goal in mind: That this information will grow proverbial wings and take flight to at last rid the red light industry of these RIDICULOUS LIES about irradiance and thereby anchor recommendations in the truth of trustworthy research!
II. Part 2 - True Irradiance and Total Optical Power
To secure accurate and effective dosages of red light therapy, we must learn the true irradiance. We use the phrase "true irradiance" because unfortunately, most red light therapy companies report inaccurate irradiance numbers based on solar powered meters and other uncalibrated light meters that yield values that can be off by as much as 400% or more! One popular red light bed company reports their irradiance at 160 mW/cm^2, but it is actually closer to 35-40 mW/cm^2. These egregious errors are far worse in full body beds than smaller panels because there is much more light present and both a top and bottom. Even with panels, irradiance numbers can be manipulated to appear twice as high as they really are. In addition to publishing the wrong irradiance values, many of these companies INCORRECTLY market the foolish notion that more irradiance is better, which as we just saw, is NOT backed up by any reputable research. And finally because we calculate the dosage by multiplying the irradiance by the time of the session, if we have an inflated irradiance number, we end up with a lower dose.
The irony is, most of these beds that claim ridiculous irradiance numbers have irradiances well under 50 mW/cm^2 and many under even 20 mW/cm^2. Here is a quick buyers guide tip: any bed you can plug into a standard wall outlet will not be able to go higher then 20 mW/cm^2 based on several tests we have performed. To get therapeutic irradiance, you need an electrician to install a higher amperage and voltage outlet (similar to dryer outlets). Very few companies have irradiances that are actually higher than 50 mW/cm^2 (we have tested only one), which typically prompts users to report a bad case of the sweats or at the very least, being uncomfortably hot. Without accurate irradiance measurements, we cannot know for sure. In fact more times than not, they are UNDERPOWERED! Let's bring their scam to light and explain the overriding problem of using solar meters. We will then explain how to properly measure light with a NIST calibrated spectroradiometer.
Note: NIST traceable calibration certifies that the lab or manufacturer in question is equipped and able to calibrate equipment to National Institute of Standards and Technology (NIST) standards and that products by that manufacturer match NIST-maintained measurement standards.
The irony is, most of these beds that claim ridiculous irradiance numbers have irradiances well under 50 mW/cm^2 and many under even 20 mW/cm^2. Here is a quick buyers guide tip: any bed you can plug into a standard wall outlet will not be able to go higher then 20 mW/cm^2 based on several tests we have performed. To get therapeutic irradiance, you need an electrician to install a higher amperage and voltage outlet (similar to dryer outlets). Very few companies have irradiances that are actually higher than 50 mW/cm^2 (we have tested only one), which typically prompts users to report a bad case of the sweats or at the very least, being uncomfortably hot. Without accurate irradiance measurements, we cannot know for sure. In fact more times than not, they are UNDERPOWERED! Let's bring their scam to light and explain the overriding problem of using solar meters. We will then explain how to properly measure light with a NIST calibrated spectroradiometer.
Note: NIST traceable calibration certifies that the lab or manufacturer in question is equipped and able to calibrate equipment to National Institute of Standards and Technology (NIST) standards and that products by that manufacturer match NIST-maintained measurement standards.
Bogus Irradiance Readings using Solar Meters - The Biggest Scam in the Red Light Therapy Industry!
One of the most important parameters of red light therapy is the intensity or irradiance measured in usually mW/cm^2! This is a physical quantity that is challenging to measure on full body red light beds, so ultimately it’s probably best to use a third party lab for confirmation. Let’s say a red light therapy company decides to measure irradiance itself. In that case, they need the right tools for the job. The great deception is that nearly all red light bed companies either avoid talking about irradiance or measure it using uncalibrated solar power meters, laser meters or other meters that are wildly inaccurate. As of this writing, it appears that only Spectra red light, Novothor and perhaps one or two others are taking the necessary steps to achieve legit irradiance measurements within a couple decimal points of accuracy for full body red light beds. It’s shocking that out of 50-plus companies that sell and distribute full body red light therapy beds, there are only a few companies properly reporting irradiance! It's all marketing hype, gimmicks and smoke and mirrors designed to seduce us into buying "the most powerful red light bed" (even though research is decisive that more is NOT better)!
One of the most important parameters of red light therapy is the intensity or irradiance measured in usually mW/cm^2! This is a physical quantity that is challenging to measure on full body red light beds, so ultimately it’s probably best to use a third party lab for confirmation. Let’s say a red light therapy company decides to measure irradiance itself. In that case, they need the right tools for the job. The great deception is that nearly all red light bed companies either avoid talking about irradiance or measure it using uncalibrated solar power meters, laser meters or other meters that are wildly inaccurate. As of this writing, it appears that only Spectra red light, Novothor and perhaps one or two others are taking the necessary steps to achieve legit irradiance measurements within a couple decimal points of accuracy for full body red light beds. It’s shocking that out of 50-plus companies that sell and distribute full body red light therapy beds, there are only a few companies properly reporting irradiance! It's all marketing hype, gimmicks and smoke and mirrors designed to seduce us into buying "the most powerful red light bed" (even though research is decisive that more is NOT better)!

The Problem with Solar Power Meters Exposed
Solar power meters are designed to measure a broad spectrum of light, including white light, sunlight and grow lights. The calibration is thus made for the full spectrum range of the sun to accurately estimate the equivalent "solar" output of a light source. These powerful solar power meters use a silicon photodiode to take the measurement that must be calibrated and corrected to adjust for their sensitivity curves. Let's take a closer look at this OVERWHELMING problem!
We see here the typical spectral response with a silicon photodiode.[23] This type of diode is universal to nearly all solar power meters and many laser power meters, so they have a similar spectral response like this curve. As wavelength moves towards a peak of 980nm in infrared, our big takeaway is the dramatic rise in sensitivity
We can see this from the curve that at 980nm the response is about twice that of 500nm (.6 to .3). "A/W "refers on this graph refers to the current (amperes) produced per watt of incidental light. So even if the irradiance is same at 980 vs 500nm, 980nm creates twice the amount of electrical current and hence registers or reports at twice as much irradiance as 500nm, which leads to a 200% error. Let’s repeat that – a TWO HUNDRED PERCENT ERROR! The reason for this is the photoelectric effect and the formula E=hv. 500nm photons have roughly twice the energy of 980nm photons, meaning there will be 1/2 the number to cover the band gap of the photodiode. The high energy photons contain twice the energy they need to kick up an electron to a higher energy state (but half the photons). This extra energy ends up being lost as heat, which we do NOT measure. If the band gap is 980nm as in this example, we use all the energy of the 980nm photons to kick the electron to that higher energy state to create the current. Let’s keep in mind, there are roughly twice as many 980nm photons as 500nm photons. This is why it creates the peak amount of current. This is also how solar panels work. They have a peak wavelength response, only in their case, the current powers our house.
Research Cautioning Silicon Photodiode Power Meters
One peer-reviewed article precautions consumers against using silicon photodiode power meters for the measurement of LLLT (low level light therapy) or PBM (photobiomodulation) parameters.[24] Researchers reiterate the concerns that we make above about the sensitivity curve of the silicon photodiode:
"Although this type of measurement system is most popular within PBM/LLLT literature, measurements from these devices should be interpreted cautiously. The spectral sensitivity differs with wavelength due to the quantum efficiency of the photodiode and generally has a better response at longer wavelengths. Thus, if broadband light sources are measured, the power emitted at short and longer wavelengths maybe be under- or over-estimated, respectively."[24]
While most red light companies appear to be TOTALLY CLUELESS, scientists are fully aware that photodiode based solar power meters must be interpreted with extreme caution to avoid perceptible measurement errors. They highlight the reality that shorter wavelengths have a limited response, and higher wavelengths have an intense response, as we demonstrated in the sensitivity diagrams above.[23] It is likewise important to note that no PBM/LLLT studies use solar power meters to measure irradiance because if they did, they would not be able to get proper dosages!
Solar power meters are designed to measure a broad spectrum of light, including white light, sunlight and grow lights. The calibration is thus made for the full spectrum range of the sun to accurately estimate the equivalent "solar" output of a light source. These powerful solar power meters use a silicon photodiode to take the measurement that must be calibrated and corrected to adjust for their sensitivity curves. Let's take a closer look at this OVERWHELMING problem!
We see here the typical spectral response with a silicon photodiode.[23] This type of diode is universal to nearly all solar power meters and many laser power meters, so they have a similar spectral response like this curve. As wavelength moves towards a peak of 980nm in infrared, our big takeaway is the dramatic rise in sensitivity
We can see this from the curve that at 980nm the response is about twice that of 500nm (.6 to .3). "A/W "refers on this graph refers to the current (amperes) produced per watt of incidental light. So even if the irradiance is same at 980 vs 500nm, 980nm creates twice the amount of electrical current and hence registers or reports at twice as much irradiance as 500nm, which leads to a 200% error. Let’s repeat that – a TWO HUNDRED PERCENT ERROR! The reason for this is the photoelectric effect and the formula E=hv. 500nm photons have roughly twice the energy of 980nm photons, meaning there will be 1/2 the number to cover the band gap of the photodiode. The high energy photons contain twice the energy they need to kick up an electron to a higher energy state (but half the photons). This extra energy ends up being lost as heat, which we do NOT measure. If the band gap is 980nm as in this example, we use all the energy of the 980nm photons to kick the electron to that higher energy state to create the current. Let’s keep in mind, there are roughly twice as many 980nm photons as 500nm photons. This is why it creates the peak amount of current. This is also how solar panels work. They have a peak wavelength response, only in their case, the current powers our house.
Research Cautioning Silicon Photodiode Power Meters
One peer-reviewed article precautions consumers against using silicon photodiode power meters for the measurement of LLLT (low level light therapy) or PBM (photobiomodulation) parameters.[24] Researchers reiterate the concerns that we make above about the sensitivity curve of the silicon photodiode:
"Although this type of measurement system is most popular within PBM/LLLT literature, measurements from these devices should be interpreted cautiously. The spectral sensitivity differs with wavelength due to the quantum efficiency of the photodiode and generally has a better response at longer wavelengths. Thus, if broadband light sources are measured, the power emitted at short and longer wavelengths maybe be under- or over-estimated, respectively."[24]
While most red light companies appear to be TOTALLY CLUELESS, scientists are fully aware that photodiode based solar power meters must be interpreted with extreme caution to avoid perceptible measurement errors. They highlight the reality that shorter wavelengths have a limited response, and higher wavelengths have an intense response, as we demonstrated in the sensitivity diagrams above.[23] It is likewise important to note that no PBM/LLLT studies use solar power meters to measure irradiance because if they did, they would not be able to get proper dosages!

Examples of "The Problem"
Example 1: This image uses a popular and relatively inexpensive ($88) solar power meter showing an inaccurate reading of 180 mW/cm^2 taken on a best-selling red light therapy bed. We know it’s off because we took this measurement ourselves and compared it to a NIST lab-calibrated spectroradiometer (and verified by a third party testing company Lightlab), which revealed a true irradiance of 45 mW/cm^2!
Example 2: A “leading” red light bed company (in sales, anyway) lists 100 mW/cm2 for their bed. The dead giveaway that this is an absolutely deceptive reading is that they boast that we can plug it into a standard wall outlet! Most higher-powered devices require an electrician to come to our house or office to install a 20 to 40-amp 220-volt breaker because we need more electricity to fire up a more powerful Red Light BED. They “claim” they are energy efficient, but no amount of efficiency is able to create 100 mW/ cm2 from a standard power outlet! The real reason they list 100mW/cm^2 is – what else? - deceptive marketing with cheap solar power meters. Note: we did some tests with an extremely energy efficient bed and the most irradiance you can get from a full body bed that plugs into a standard wall outlet is 20 mW/cm^2. And that is a best case scenario. Any bed that plugs into a standard wall outlet is likely to be even less!
Example 3: The owner of another popular red light bed company whose website boasts an irradiance of 150 mW/cm^2, ADMITTED IT WAS NOT ACCURATE! His excuse? Of course - blame it on the web designer, who wrote that misinformation because so many competing beds were doing it. Just because other companies are deceiving their customers, that’s no excuse to lie to yours! It’s really a pity that there is so much deception about irradiance in this industry. Without an accurate irradiance reading, we cannot get accurate dosing. What started out as ignorance is now an unscrupulous marketing practice and industry-wide cover-up.
Example 1: This image uses a popular and relatively inexpensive ($88) solar power meter showing an inaccurate reading of 180 mW/cm^2 taken on a best-selling red light therapy bed. We know it’s off because we took this measurement ourselves and compared it to a NIST lab-calibrated spectroradiometer (and verified by a third party testing company Lightlab), which revealed a true irradiance of 45 mW/cm^2!
Example 2: A “leading” red light bed company (in sales, anyway) lists 100 mW/cm2 for their bed. The dead giveaway that this is an absolutely deceptive reading is that they boast that we can plug it into a standard wall outlet! Most higher-powered devices require an electrician to come to our house or office to install a 20 to 40-amp 220-volt breaker because we need more electricity to fire up a more powerful Red Light BED. They “claim” they are energy efficient, but no amount of efficiency is able to create 100 mW/ cm2 from a standard power outlet! The real reason they list 100mW/cm^2 is – what else? - deceptive marketing with cheap solar power meters. Note: we did some tests with an extremely energy efficient bed and the most irradiance you can get from a full body bed that plugs into a standard wall outlet is 20 mW/cm^2. And that is a best case scenario. Any bed that plugs into a standard wall outlet is likely to be even less!
Example 3: The owner of another popular red light bed company whose website boasts an irradiance of 150 mW/cm^2, ADMITTED IT WAS NOT ACCURATE! His excuse? Of course - blame it on the web designer, who wrote that misinformation because so many competing beds were doing it. Just because other companies are deceiving their customers, that’s no excuse to lie to yours! It’s really a pity that there is so much deception about irradiance in this industry. Without an accurate irradiance reading, we cannot get accurate dosing. What started out as ignorance is now an unscrupulous marketing practice and industry-wide cover-up.
Example 4 (the most ridiculous example of all- 960 mW/cm^2??): One company not only failed to use the correct meter to measure irradiance, but also reported surreally impossible values of 960 mW/cm^2 on their comparison chart. The first error was that they did not measure irradiance properly. But they also got their units wrong! 960 W/m^2 = 96 mW/cm^2 (to convert move the decimal place). That is, they were reading W/m^2 on their meter (probably a solar meter) and reporting it as mW/cm^2. Their comparison chart listed all the dosage calculations incorrectly when accurate dosage is critical for getting the optimal benefit. We have seen that overdosing leads to negative effects like increased ROS, RNS, lower penetration depth, and fewer benefits. Again, MORE IS NOT BETTER! However, this bed is very likely closer to 50 mW/cm^2 which based on our tests is too much (and too hot) ! Unfortunately, people that have used this bed reported that they started sweating soon after getting in and even worse, their skin started to burn!
Another Scam - More LEDs is better??
Some red light bed manufacturers make the bogus claim that more LEDs is the better way to go. A few companies even make this their focal selling point by highlighting the number of LEDs on their comparison charts!! This is patently absurd, because it’s the equivalent of declaring that having four 25 watt lightbulbs is better than one 100 watt lightbulb. We can have few LEDs with more power (like 2 Watt LEDs compared to 1 Watt LEDs). Having more LEDs at a lower power is not better than fewer LEDs a higher power? Come on! This is straight up bad science and MARKETING DECEPTION!
These manipulative companies continue their con by saying more LEDs gives us a better spread of light. Yet this too is untrue because we can adjust the beam angle of fewer and more powerful LEDs to create not only an effective, but even a BETTER distribution of light using FEWER LEDs at a higher power. Can we see how ridiculous this is? Most companies rely on marketing gimmicks like this, not real science. The ONLY THINGS that matter are the measured irradiance and verified wavelengths at the skin using a lab calibrated spectroradiometer. We can add having a uniform distribution of light and low EMF as well. Everything else is just marketing gimmicks and "phony-baloney" tactics.
Some red light bed manufacturers make the bogus claim that more LEDs is the better way to go. A few companies even make this their focal selling point by highlighting the number of LEDs on their comparison charts!! This is patently absurd, because it’s the equivalent of declaring that having four 25 watt lightbulbs is better than one 100 watt lightbulb. We can have few LEDs with more power (like 2 Watt LEDs compared to 1 Watt LEDs). Having more LEDs at a lower power is not better than fewer LEDs a higher power? Come on! This is straight up bad science and MARKETING DECEPTION!
These manipulative companies continue their con by saying more LEDs gives us a better spread of light. Yet this too is untrue because we can adjust the beam angle of fewer and more powerful LEDs to create not only an effective, but even a BETTER distribution of light using FEWER LEDs at a higher power. Can we see how ridiculous this is? Most companies rely on marketing gimmicks like this, not real science. The ONLY THINGS that matter are the measured irradiance and verified wavelengths at the skin using a lab calibrated spectroradiometer. We can add having a uniform distribution of light and low EMF as well. Everything else is just marketing gimmicks and "phony-baloney" tactics.
Concluding Thoughts: Unethical Marketing Part 2 (Why is this Happening)?
Two raging lies have pervaded the Red Light Therapy industry for many years now. The first is that red light bed companies and so-called experts have falsely advertised their intensity by an EXTREMELY wide margin. They use solar power meters, laser meters, grow light meters, etc. which yield falsely high values in the Red/NIR wavelength range. The second lie is that more intensity or irradiance is better with seemingly no upper bound irradiance (one company even claims to have 960 mW/cm^2)?!
Why is this Happening?
1) Deceptive Marketing: Saying you have the most high-powered red light bed serves a powerful marketing angle. If the prevailing wisdom is that more irradiance is better, companies will be motivated to lie that their bed or panel has the most irradiance at whatever the cost, even if it means fudging the results with solar meters. It seems as though companies keep upping each other with ever-higher irradiance numbers, which is grossly out of touch with the reality proven by actual research.
2) Excuses: A clever excuse these companies often make is that they only solar power meters for comparison purposes. They blatantly admit their numbers are inaccurate, but want to make sure their product is compared to others using the same method, albeit bogus and incorrect. Just because "everybody else is doing it" is no excuse to share incorrect information.
3) Passing on bad information: Another favorite excuse is that Chinese suppliers report false numbers, so sometimes companies just blindly pass on these incorrect measurements. But they shouldn’t be allowed to change the measurement standard simply because other red light therapy companies ignorantly trusted the solar power meter measurements from their Chinese red light therapy suppliers.
Two raging lies have pervaded the Red Light Therapy industry for many years now. The first is that red light bed companies and so-called experts have falsely advertised their intensity by an EXTREMELY wide margin. They use solar power meters, laser meters, grow light meters, etc. which yield falsely high values in the Red/NIR wavelength range. The second lie is that more intensity or irradiance is better with seemingly no upper bound irradiance (one company even claims to have 960 mW/cm^2)?!
Why is this Happening?
1) Deceptive Marketing: Saying you have the most high-powered red light bed serves a powerful marketing angle. If the prevailing wisdom is that more irradiance is better, companies will be motivated to lie that their bed or panel has the most irradiance at whatever the cost, even if it means fudging the results with solar meters. It seems as though companies keep upping each other with ever-higher irradiance numbers, which is grossly out of touch with the reality proven by actual research.
2) Excuses: A clever excuse these companies often make is that they only solar power meters for comparison purposes. They blatantly admit their numbers are inaccurate, but want to make sure their product is compared to others using the same method, albeit bogus and incorrect. Just because "everybody else is doing it" is no excuse to share incorrect information.
3) Passing on bad information: Another favorite excuse is that Chinese suppliers report false numbers, so sometimes companies just blindly pass on these incorrect measurements. But they shouldn’t be allowed to change the measurement standard simply because other red light therapy companies ignorantly trusted the solar power meter measurements from their Chinese red light therapy suppliers.

B. Correct Irradiance Readings Using Spectroradiometers (or third party labs)
Method 1 Use a Lab Grade Spectroradiometer
The only foolproof way to get precise measurements of irradiance and wavelengths in red light beds and panels is by using a spectroradiometer. A spectroradiometer is a calibrated light measurement tool able to measure accurately both the wavelength and amplitude of the light emitted from any light source (irradiance mW/cm^2). By contrast, solar meters, grow light meters and laser power meters merely measure the irradiance and do so VERY INACCURATELY unless you take great care to multiply by the correction factors (if the company even offers such a table). Even then, it can only be used as a rough approximation for A SINGLE wavelength. It becomes incredibly difficult for multiple wavelengths because we cannot know exactly the amount of irradiance coming from each wavelength with a solar meter.
Method 1 Use a Lab Grade Spectroradiometer
The only foolproof way to get precise measurements of irradiance and wavelengths in red light beds and panels is by using a spectroradiometer. A spectroradiometer is a calibrated light measurement tool able to measure accurately both the wavelength and amplitude of the light emitted from any light source (irradiance mW/cm^2). By contrast, solar meters, grow light meters and laser power meters merely measure the irradiance and do so VERY INACCURATELY unless you take great care to multiply by the correction factors (if the company even offers such a table). Even then, it can only be used as a rough approximation for A SINGLE wavelength. It becomes incredibly difficult for multiple wavelengths because we cannot know exactly the amount of irradiance coming from each wavelength with a solar meter.

With a lab calibrated spectroradiometer, we can accurately measure the irradiance at each wavelength along with the precise total irradiance to achieve a spectral irradiance plot of wavelength versus irradiance, as shown here from a Novothor bed we tested that has 660nm and 850nm. Note that the peak irradiances are close to both 660 and 850nm. When we go to the data screen, we see many specific details from the measurement, the most important being the total irradiance, which for the Novothor is approximately 28mW/cm^2.
These images are accurate, because unlike solar meters that have a peak response, spectroradiometers can measure each wavelength precisely using either a multichannel or scanning spectroradiometer. The effective wavelength (spectral) range of a spectroradiometer is determined by the grating dispersion ability and the detector’s sensitivity range. To effectively measure red light LED beds and panels, we need a spectroradiometer that is NIST-calibrated and covers 400nm-1100nm, the most common wavelengths in PBM. These include blue for acne (415nm) and green (528nm) for skin, sleep, wound healing etc. and up to the longest NIR wavelength used in some beds - 1064nm!
If we’re only interested in red and near infrared, a meter with a 600-1100nm range will do. One example of a spectroradiometer that meets all these criteria is the Spectis 5 .0, a lab-grade optical spectrometer with incredible reliability, accuracy and a dazzling digital display. They guarantee their calibration and accuracy for a year, and we can send back to get recalibrated! But it costs about $20,000 and proper training requires dedication and diligence. We mention the Spectis 5 .0 because this particular spectroradiometer is used by the only two companies (Novothor and Spectra Red Light) working with a properly calibrated device! No other red light bed manufacturer showcases accurate irradiance readings with a lab-grade, certified and calibrated meter (as of this writing). This is one of only two ways to guarantee that we are getting the irradiance (and wavelengths) promised by the manufacturer! Again, proper dosing critically depends on accurate irradiance measurements. Imagine buying a bottle of vitamin C pills listing 1000mg per tablet when in reality they only had 250mg. The dosing would be way off because the amount is listed wrong. This precisely what happens with inflated red light irradiance readings from nearly all the companies that list irradiance using cheap and inaccurate solar, grow light or laser power meters. Sadly, it seems like hiding the truth and outright lying are the norm, rather than the exception.
If we’re only interested in red and near infrared, a meter with a 600-1100nm range will do. One example of a spectroradiometer that meets all these criteria is the Spectis 5 .0, a lab-grade optical spectrometer with incredible reliability, accuracy and a dazzling digital display. They guarantee their calibration and accuracy for a year, and we can send back to get recalibrated! But it costs about $20,000 and proper training requires dedication and diligence. We mention the Spectis 5 .0 because this particular spectroradiometer is used by the only two companies (Novothor and Spectra Red Light) working with a properly calibrated device! No other red light bed manufacturer showcases accurate irradiance readings with a lab-grade, certified and calibrated meter (as of this writing). This is one of only two ways to guarantee that we are getting the irradiance (and wavelengths) promised by the manufacturer! Again, proper dosing critically depends on accurate irradiance measurements. Imagine buying a bottle of vitamin C pills listing 1000mg per tablet when in reality they only had 250mg. The dosing would be way off because the amount is listed wrong. This precisely what happens with inflated red light irradiance readings from nearly all the companies that list irradiance using cheap and inaccurate solar, grow light or laser power meters. Sadly, it seems like hiding the truth and outright lying are the norm, rather than the exception.

This image is of an affordable Hopocolor spectroradiometer with a visual display, which we also own and regularly use and send to prospects so they can see false irradiance values for themselves. While it’s not NIST-calibrated, when we compare this to our Spectis, the numbers are very close within a small error margin - less than 5% compared to a 200-400% error with solar power meters! Several renowned red light influencers and reviewers like Alex Fergus use this meter to expose bogus irradiance numbers. We must be sure to get one with the right range of wavelengths as most red light panels and beds require at least 600-1000nm. If we want to stir things up a little, let’s hightail it to a wellness or biohacking trade show or health expo that has many red light bed "booths" and take this meter around and test different red light beds. We would surely find that unscrupulous companies wouldn’t let us in their booth to test their bed and might even chase us away lest we expose their volcano of lies!

Method 2 - The BEST method to measure light - Use an Accredited Third-Party Lab Like LightLab.
Another alternative is securing a third party lab test like LightLab International to test the bed . This type of lab result is the most definitive because it is done accurately by an unbiased third party. This is THE ONLY way we can trust that a company has the irradiance it claims. Even a spectroradiometer reading done by a single untrained person can have inaccurate outcomes, albeit still MUCH more accurate than solar power meters.
Here are some reasons to get to a professional third party testing lab like Lightlab to verify the irradiance:
1. You can have trained professionals properly take the measurements with the correct equipment and interpret the results.
2. The equipment is always properly calibrated and tested with a lab grade light source.
3. Measurements are taken in a way to control for stray light.
4, Unlike the untrained amateur who may not understand the intricacies and nuances of testing, professionals will not use incorrect settings like the wrong integration time.
5. They follow industry standard testing protocols for accuracy and repeatability.
6. It removes any personal bias that we would bring to the process if we measured it ourselves. Based on what I have observed in this industry, I personally suggest ONLY trusting a third party test OR measuring the light yourselves with a Hopocolor. Let’s not just blindly believe irradiance numbers!!
Very Important Note: For red light beds, the top needs to be blocked when measuring the bottom and the bottom needs to be blocked when measuring the top. As it turns on, measuring the light of both top and bottom increases and skews the numbers by a whopping additional 60%! Most deceptive companies use solar power meters and measure the light in the middle with the top and bottom both ON!! Not only do they get more than double the irradiance from the photodiode alone, they FURTHER SKEW the numbers by measuring the light with both the top and bottom turned on. This is likely why red light bed measurements with solar meters can be 400% too high versus red light panels with solar meters being only 200% too high. Other factors include improper cosine corrections so more light is measured than should be - and also not blocking and factoring out background light. All these measurement errors INCREASE irradiance even further, even beyond the solar power meters’ skewed outputs.
Why it's best to do BOTH!
We should also mention that even if we get a third party test - which I think should be mandatory in the industry – it's still worth investing in a lab calibrated spectroradiometer and learning how to measure light properly ourselves. This allows for every bed to be tested for irradiance before it even ships. As of this writing, ONLY Novothor and Spectra Red Light are testing the wavelengths and irradiance of each bed before they ship, and can provide a detailed report if requested. This way, each bed can be certified to have the claimed irradiance! While all this should be normal, especially for beds that cost up to $100,000 or more, sadly very few companies are doing either one of these, let alone both. This is the only way to have accurate and transparent irradiance measurements. It is our hope that with the research presented in this book and leaders like Spectra red light and Novothor on board, the industry will soon be "cleaned up" from all the irradiance lies and deception.
Testing and Verifying Wavelengths [Important]
We should demand from any red light bed or panel company a verification of the wavelengths they claim; we need a spectroradiometer for this, too. I found one company that claimed to have 660nm LEDs, but when I tested it, it was only 630nm!! Again, without testing, we end up having to blindly believe red light companies and marketers, many of which we have found to be unscrupulous.
Another alternative is securing a third party lab test like LightLab International to test the bed . This type of lab result is the most definitive because it is done accurately by an unbiased third party. This is THE ONLY way we can trust that a company has the irradiance it claims. Even a spectroradiometer reading done by a single untrained person can have inaccurate outcomes, albeit still MUCH more accurate than solar power meters.
Here are some reasons to get to a professional third party testing lab like Lightlab to verify the irradiance:
1. You can have trained professionals properly take the measurements with the correct equipment and interpret the results.
2. The equipment is always properly calibrated and tested with a lab grade light source.
3. Measurements are taken in a way to control for stray light.
4, Unlike the untrained amateur who may not understand the intricacies and nuances of testing, professionals will not use incorrect settings like the wrong integration time.
5. They follow industry standard testing protocols for accuracy and repeatability.
6. It removes any personal bias that we would bring to the process if we measured it ourselves. Based on what I have observed in this industry, I personally suggest ONLY trusting a third party test OR measuring the light yourselves with a Hopocolor. Let’s not just blindly believe irradiance numbers!!
Very Important Note: For red light beds, the top needs to be blocked when measuring the bottom and the bottom needs to be blocked when measuring the top. As it turns on, measuring the light of both top and bottom increases and skews the numbers by a whopping additional 60%! Most deceptive companies use solar power meters and measure the light in the middle with the top and bottom both ON!! Not only do they get more than double the irradiance from the photodiode alone, they FURTHER SKEW the numbers by measuring the light with both the top and bottom turned on. This is likely why red light bed measurements with solar meters can be 400% too high versus red light panels with solar meters being only 200% too high. Other factors include improper cosine corrections so more light is measured than should be - and also not blocking and factoring out background light. All these measurement errors INCREASE irradiance even further, even beyond the solar power meters’ skewed outputs.
Why it's best to do BOTH!
We should also mention that even if we get a third party test - which I think should be mandatory in the industry – it's still worth investing in a lab calibrated spectroradiometer and learning how to measure light properly ourselves. This allows for every bed to be tested for irradiance before it even ships. As of this writing, ONLY Novothor and Spectra Red Light are testing the wavelengths and irradiance of each bed before they ship, and can provide a detailed report if requested. This way, each bed can be certified to have the claimed irradiance! While all this should be normal, especially for beds that cost up to $100,000 or more, sadly very few companies are doing either one of these, let alone both. This is the only way to have accurate and transparent irradiance measurements. It is our hope that with the research presented in this book and leaders like Spectra red light and Novothor on board, the industry will soon be "cleaned up" from all the irradiance lies and deception.
Testing and Verifying Wavelengths [Important]
We should demand from any red light bed or panel company a verification of the wavelengths they claim; we need a spectroradiometer for this, too. I found one company that claimed to have 660nm LEDs, but when I tested it, it was only 630nm!! Again, without testing, we end up having to blindly believe red light companies and marketers, many of which we have found to be unscrupulous.
Note: We can't use wattage to calculate irradiance. We found a large error in Ari Whitten's otherwise solid and popular Red Light Therapy book. The LEDs are interconnected to the output of power supplies, which can be overpowered or underpowered, so all the power is NOT going to the LEDs. The measurements depend on the distance away, so irradiance measured by the power supplies of the bed or panel are NOT accurate! We cannot repeat this truth enough! The ONLY way get accurate irradiance measurements is taking actual measurements using a lab calibrated spectroradiometer or have a third party company do it.

The Importance of Having a Uniform Distribution of Light
Along with therapeutic and research proven wavelengths, we must make sure the light is evenly distributed over all the present wavelengths. We have seen some beds with large gaps between sections that lead to a uniform distribution of light. Only problem is, we end up with more irradiance in some spots compared to others (hot spots) which gives "lumpy light" which is sadly a problem in MOST beds with notable exceptions like Novothor and Spectra Red light).
Also you want an even distribution between top and bottom of the bed. Because the LEDs are closer to your skin on the bottom, all beds we have tested have higher irradiance on the bottom versus the top. This means the backside of your body is getting more irradiance than the top of your body. Only the Spectra Red light beds have an even distribution both across the bed and between both top and bottom. This is accomplished by using a narrower beam angle on the top to even things out and get a similar irradiance to the bottom.
Another related problem is adding too few LEDs for any given wavelength. For example, one company has a LED panel with added blue but they only put six blue LEDs on the entire panel! This leads to not only a lack of uniformity but NOT ENOUGH irradiance for the blue wavelength. Essentially and unfortunately, the blue light ends up being more for decoration than therapy.
Along with therapeutic and research proven wavelengths, we must make sure the light is evenly distributed over all the present wavelengths. We have seen some beds with large gaps between sections that lead to a uniform distribution of light. Only problem is, we end up with more irradiance in some spots compared to others (hot spots) which gives "lumpy light" which is sadly a problem in MOST beds with notable exceptions like Novothor and Spectra Red light).
Also you want an even distribution between top and bottom of the bed. Because the LEDs are closer to your skin on the bottom, all beds we have tested have higher irradiance on the bottom versus the top. This means the backside of your body is getting more irradiance than the top of your body. Only the Spectra Red light beds have an even distribution both across the bed and between both top and bottom. This is accomplished by using a narrower beam angle on the top to even things out and get a similar irradiance to the bottom.
Another related problem is adding too few LEDs for any given wavelength. For example, one company has a LED panel with added blue but they only put six blue LEDs on the entire panel! This leads to not only a lack of uniformity but NOT ENOUGH irradiance for the blue wavelength. Essentially and unfortunately, the blue light ends up being more for decoration than therapy.

If we go by research-proven irradiance ranges, we want at least 5mW/cm^2 (ideally) per wavelength. The best possible scenario for THE ULTIMATE, EFFECTIVE red light therapy bed or panel is to have eight to 10 different wavelengths to blanket therapeutically proven ranges of wavelengths with at least half maximum (FWHM). We must then ensure that the light is evenly distributed to give a TOTAL irradiance in the neighborhood of 30-35 mW/cm^2 but no more than 40mW/cm^2. We must have at least 5mW/cm^2 at each given wavelength (ideally).
We have a few intriguing strategies to create a uniform blend of light. First, we can use various lenses and adjust the beam angle to ensure that the light blends properly. Another capital idea is using frosted acrylic, which also helps spread the light more evenly. Remember, irradiance measurements at the skin are what matters, don't listen to marketing nonsense that you need more LEDs for even spread or that frosted acrylic blocks the light). This is an important takeaway from this chapter - ALL that matters are field measurements of light at the skin. Having more LEDs, or having LEDs closer to the surface makes NO DIFFERENCE whatsoever!! All that matters is actual irradiance measurements at the contact point of the skin. I emphasize this because there is SO MUCH marketing deception around this.
To test uniformity of light, we can measure a large sample of random points and calculate the mean and sample standard deviation. The standard deviation gives us a sense of the uniformity of irradiance. Ideally, we want this to be zero - no variance - which means a perfectly even distribution. In reality, this is not possible, yet we can get the standard deviation to within 1-2mW/cm^2. We have performed this test and observed that some beds have a much larger variation where light is clumpier, which is not ideal. The most definitive “map” would be an isoirradiance plot like we show here done by a third party lab. While achieving accurate irradiance measurements is our highest priority, the test of light uniformity is also important.
We have a few intriguing strategies to create a uniform blend of light. First, we can use various lenses and adjust the beam angle to ensure that the light blends properly. Another capital idea is using frosted acrylic, which also helps spread the light more evenly. Remember, irradiance measurements at the skin are what matters, don't listen to marketing nonsense that you need more LEDs for even spread or that frosted acrylic blocks the light). This is an important takeaway from this chapter - ALL that matters are field measurements of light at the skin. Having more LEDs, or having LEDs closer to the surface makes NO DIFFERENCE whatsoever!! All that matters is actual irradiance measurements at the contact point of the skin. I emphasize this because there is SO MUCH marketing deception around this.
To test uniformity of light, we can measure a large sample of random points and calculate the mean and sample standard deviation. The standard deviation gives us a sense of the uniformity of irradiance. Ideally, we want this to be zero - no variance - which means a perfectly even distribution. In reality, this is not possible, yet we can get the standard deviation to within 1-2mW/cm^2. We have performed this test and observed that some beds have a much larger variation where light is clumpier, which is not ideal. The most definitive “map” would be an isoirradiance plot like we show here done by a third party lab. While achieving accurate irradiance measurements is our highest priority, the test of light uniformity is also important.
Conclusion to one of the most important chapters in this book
Irradiance is one of the three major parameters we need to confidently understand in any red light therapy bed or panel to ensure proper dosing. We have seen in this chapter conclusive evidence that more irradiance is NOT only NOT better, but can actually cause more harm than good. Going by nature's guidance, photobiomodulation research, and myriad full body red light led studies, the goldilocks window of irradiance is around 16-40 mW/cm^2. If we use nature's sweet spot, it’s even better at 30-35 mW/cm^2. More is definitely not better, and when we go above 40-50 mW/cm^2 we end up with tissue heating and overdosing. This overdosing can cause oxidative stress (increased ROS), INCREASE INFLAMMATION and extensively damage the cells, much like overexercising and overtraining does. Remember, red light is an exercise mimetic.
To know exactly what the irradiance is in any bed or panel, we need to use a lab calibrated spectroradiometer, NOT a solar power meter. The biggest scam in the red light panel and bed industry is the reporting of wildly inflated irradiances based on the use of wrong equipment. Our investigation reveals that the errors are almost always in the 200-400% range (or more!). Companies are claiming twice to four times as much irradiance (and in one instance ten times) than they actually have! This is pure deception, with the added irony that many of these beds are either in the therapeutic range or many times they are underpowered. There are only one or two companies that ACTUALLY use too much irradiance, like the one company we mentioned whose users sweat and get burned. These companies need to decide: Are they making unsafe red light therapy beds, or over-exaggerating their intensity numbers (or both)?
The reason we need precise irradiance values from a lab calibrated spectroradiometer or third party testing company is that proper dosing is only possible with correct irradiance numbers. In the next chapter, we will further explore dosing and confirm with even greater certainty that more is not better - not only with irradiance but also time and frequency of sessions. We can still overdo it with a bed that has 30-35 mW/cm^2 (the ideal irradiance) if we engage in sessions too frequently and/or too long. Let's now turn our attention to red light therapy dosimetry, i.e. proper dosing recommendations.
Irradiance is one of the three major parameters we need to confidently understand in any red light therapy bed or panel to ensure proper dosing. We have seen in this chapter conclusive evidence that more irradiance is NOT only NOT better, but can actually cause more harm than good. Going by nature's guidance, photobiomodulation research, and myriad full body red light led studies, the goldilocks window of irradiance is around 16-40 mW/cm^2. If we use nature's sweet spot, it’s even better at 30-35 mW/cm^2. More is definitely not better, and when we go above 40-50 mW/cm^2 we end up with tissue heating and overdosing. This overdosing can cause oxidative stress (increased ROS), INCREASE INFLAMMATION and extensively damage the cells, much like overexercising and overtraining does. Remember, red light is an exercise mimetic.
To know exactly what the irradiance is in any bed or panel, we need to use a lab calibrated spectroradiometer, NOT a solar power meter. The biggest scam in the red light panel and bed industry is the reporting of wildly inflated irradiances based on the use of wrong equipment. Our investigation reveals that the errors are almost always in the 200-400% range (or more!). Companies are claiming twice to four times as much irradiance (and in one instance ten times) than they actually have! This is pure deception, with the added irony that many of these beds are either in the therapeutic range or many times they are underpowered. There are only one or two companies that ACTUALLY use too much irradiance, like the one company we mentioned whose users sweat and get burned. These companies need to decide: Are they making unsafe red light therapy beds, or over-exaggerating their intensity numbers (or both)?
The reason we need precise irradiance values from a lab calibrated spectroradiometer or third party testing company is that proper dosing is only possible with correct irradiance numbers. In the next chapter, we will further explore dosing and confirm with even greater certainty that more is not better - not only with irradiance but also time and frequency of sessions. We can still overdo it with a bed that has 30-35 mW/cm^2 (the ideal irradiance) if we engage in sessions too frequently and/or too long. Let's now turn our attention to red light therapy dosimetry, i.e. proper dosing recommendations.
References Chapter 11
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[6] Ying-Ying Huang, Aaron C.-H. Chen, and Michael R. Hamblin. Biphasic Dose Response in Low-Level Light Therapy
Dose Response. 2009; 7(4): 358–383.
[7] Barolet D. Near-Infrared Light and Skin: Why Intensity Matters. Curr Probl Dermatol. 2021;55:374-384
[8] Huang YY, Sharma SK, Carroll J, Hamblin MR. Biphasic dose response in low level light therapy - an update. Dose Response. 2011;9(4):602-18.
[9] Ahmed, S., Bewsh, G., Bhat, S., & Babu, R. (2013). LOW LEVEL LASER THERAPY: HEALING AT THE SPEED OF LIGHT. Journal of Evolution of medical and Dental Sciences, 2, 7441-7463.
[10] Dungel, Peter et al. “Wavelength-Dependent Effects of Photobiomodulation for Wound Care in Diabetic Wounds.” International journal of molecular sciences vol. 24,6 5895. 20 Mar. 2023
[11] Infrared and skin: Friend or foe. Barolet D1, Christiaens F2, Hamblin MR3. J Photochem Photobiol B. 2016 Feb;155:78-85.
[12] Temperature threshold for burn injury: an oximeter safety study. Greenhalgh DG1, Lawless MB, Chew BB, Crone WA, Fein ME, Palmieri TL. J Burn Care Rehabil. 2004 Sep-Oct;25(5):411-5.
[13] Kim, S., Jeong, S. Effects of temperature-dependent optical properties on the fluence rate and temperature of biological tissue during low-level laser therapy. Lasers Med Sci 29, 637–644 (2014).
[14] Cronshaw, M., Parker, S., & Arany, P. (2019). Feeling the Heat: Evolutionary and Microbial Basis for the Analgesic Mechanisms of Photobiomodulation Therapy. Photobiomodulation, Photomedicine, and Laser Surgery.
[15] Sommer AP, Mester AR, Trelles MA. Tuning the mitochondrial rotary motor with light. Ann Transl Med. 2015;3(22):346.
[16] Sturla Haslerud, Ingvill Fjell Naterstad, Jan Magnus Bjordal, Rodrigo Alvaro Brandão Lopes-Martins, Liv Heide Magnussen, Patrícia Sardinha Leonardo, Ricardo Henrique Marques, and Jon Joensen.Photomedicine and Laser Surgery.Oct 2017.567-575
[17] Heiskanen V, Hamblin MR. Photobiomodulation: lasers vs. light emitting diodes? Photochem Photobiol Sci. 2018 Aug 8;17(8):1003-1017.
[18] Healed by Light https://www.digikey.com/en/articles/techzone/2014/jul/healed-by-light
Journal of Photochemistry and Photobiology B: Biology,Volume 155,2016,Pages 78-85,ISSN 1011-1344,
[19] HeelSpurs LED http://heelspurs.com/led.html
[20] Kourkoumelis, Nikolaos & Tzaphlidou, Margaret. (2011). Eye Safety Related to Near Infrared Radiation Exposure to Biometric Devices. TheScientificWorldJournal. 11. 520-8.
[21] https://www.renesas.com/us/en/doc/application-note/an1737.pdf
[22] Huang YY, Chen AC, Carroll JD, Hamblin MR. Biphasic dose response in low level light therapy. Dose Response. 2009 Sep 1;7(4):358-83
[23] https://commons.wikimedia.org/wiki/File:Response_silicon_photodiode.svg
[24] Hadis, M.A., Zainal, S.A., Holder, M.J. et al. The dark art of light measurement: accurate radiometry for low-level light therapy. Lasers Med Sci 31, 789–809 (2016). https://doi.org/10.1007/s10103-016-1914-y
[25] A. P. Castano et al., “Low-level laser therapy for zymosan-induced arthritis in rats: Importance of illumination time,” Lasers Surgery Med. 39(6), 543–550 (2007).
[26] R. J. Lanzafame et al., “Reciprocity of exposure time and irradiance on energy density during photoradiation on wound healing in a murine pressure ulcer model,” Lasers Surgery Med. 39(6), 534–542 (2007).
[27] J. T. Hashmi et al., “Effect of Pulsing in Low-Level Light Therapy,” Lasers Surgery Med. 42(6), 450–466 (2010).
[28] R. Chow et al., “Inhibitory effects of laser irradiation on peripheral Mammalian nerves and relevance to analgesic effects: a systematic review,” Photomed. Laser Surgery 29(6), 365–381 (2011).
[1] Rojas, J.C., Gonzalez-Lima, F., 2011. Low level light therapy of the eye and brain. Eye Brain 3, 4967.
[2] Jenkins, P.A., Carroll, J.D., 2011. How to report low-level laser therapy (LLLT)/photomedicine dose and beam parameters in clinical and laboratory
studies. Photomed. Laser Surg. 29 (12), 785787.
[3] Henderson, T.A., Morries, L.D., 2015b. Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain?
Neuropsychiatr. Dis. Treat. 11, 21912208.
[4] Hart, Nathan S. Fitzgerald, Melinda. A New Perspective On Delivery of Red-Near-Infrared light therapy for disorders of the brain. September 19th, 2016 http://www.discoverymedicine.com/Nathan-S-Hart/2016/09/a-new-perspective-on-delivery-of-red-near-infrared-light-therapy-for-disorders-of-the-brain/
[5] Barolet D, Christiaens F, Hamblin MR. Infrared and Skin: Friend or Foe. J Photochem Photobiol B. 2016.
[6] Ying-Ying Huang, Aaron C.-H. Chen, and Michael R. Hamblin. Biphasic Dose Response in Low-Level Light Therapy
Dose Response. 2009; 7(4): 358–383.
[7] Barolet D. Near-Infrared Light and Skin: Why Intensity Matters. Curr Probl Dermatol. 2021;55:374-384
[8] Huang YY, Sharma SK, Carroll J, Hamblin MR. Biphasic dose response in low level light therapy - an update. Dose Response. 2011;9(4):602-18.
[9] Ahmed, S., Bewsh, G., Bhat, S., & Babu, R. (2013). LOW LEVEL LASER THERAPY: HEALING AT THE SPEED OF LIGHT. Journal of Evolution of medical and Dental Sciences, 2, 7441-7463.
[10] Dungel, Peter et al. “Wavelength-Dependent Effects of Photobiomodulation for Wound Care in Diabetic Wounds.” International journal of molecular sciences vol. 24,6 5895. 20 Mar. 2023
[11] Infrared and skin: Friend or foe. Barolet D1, Christiaens F2, Hamblin MR3. J Photochem Photobiol B. 2016 Feb;155:78-85.
[12] Temperature threshold for burn injury: an oximeter safety study. Greenhalgh DG1, Lawless MB, Chew BB, Crone WA, Fein ME, Palmieri TL. J Burn Care Rehabil. 2004 Sep-Oct;25(5):411-5.
[13] Kim, S., Jeong, S. Effects of temperature-dependent optical properties on the fluence rate and temperature of biological tissue during low-level laser therapy. Lasers Med Sci 29, 637–644 (2014).
[14] Cronshaw, M., Parker, S., & Arany, P. (2019). Feeling the Heat: Evolutionary and Microbial Basis for the Analgesic Mechanisms of Photobiomodulation Therapy. Photobiomodulation, Photomedicine, and Laser Surgery.
[15] Sommer AP, Mester AR, Trelles MA. Tuning the mitochondrial rotary motor with light. Ann Transl Med. 2015;3(22):346.
[16] Sturla Haslerud, Ingvill Fjell Naterstad, Jan Magnus Bjordal, Rodrigo Alvaro Brandão Lopes-Martins, Liv Heide Magnussen, Patrícia Sardinha Leonardo, Ricardo Henrique Marques, and Jon Joensen.Photomedicine and Laser Surgery.Oct 2017.567-575
[17] Heiskanen V, Hamblin MR. Photobiomodulation: lasers vs. light emitting diodes? Photochem Photobiol Sci. 2018 Aug 8;17(8):1003-1017.
[18] Healed by Light https://www.digikey.com/en/articles/techzone/2014/jul/healed-by-light
Journal of Photochemistry and Photobiology B: Biology,Volume 155,2016,Pages 78-85,ISSN 1011-1344,
[19] HeelSpurs LED http://heelspurs.com/led.html
[20] Kourkoumelis, Nikolaos & Tzaphlidou, Margaret. (2011). Eye Safety Related to Near Infrared Radiation Exposure to Biometric Devices. TheScientificWorldJournal. 11. 520-8.
[21] https://www.renesas.com/us/en/doc/application-note/an1737.pdf
[22] Huang YY, Chen AC, Carroll JD, Hamblin MR. Biphasic dose response in low level light therapy. Dose Response. 2009 Sep 1;7(4):358-83
[23] https://commons.wikimedia.org/wiki/File:Response_silicon_photodiode.svg
[24] Hadis, M.A., Zainal, S.A., Holder, M.J. et al. The dark art of light measurement: accurate radiometry for low-level light therapy. Lasers Med Sci 31, 789–809 (2016). https://doi.org/10.1007/s10103-016-1914-y
[25] A. P. Castano et al., “Low-level laser therapy for zymosan-induced arthritis in rats: Importance of illumination time,” Lasers Surgery Med. 39(6), 543–550 (2007).
[26] R. J. Lanzafame et al., “Reciprocity of exposure time and irradiance on energy density during photoradiation on wound healing in a murine pressure ulcer model,” Lasers Surgery Med. 39(6), 534–542 (2007).
[27] J. T. Hashmi et al., “Effect of Pulsing in Low-Level Light Therapy,” Lasers Surgery Med. 42(6), 450–466 (2010).
[28] R. Chow et al., “Inhibitory effects of laser irradiation on peripheral Mammalian nerves and relevance to analgesic effects: a systematic review,” Photomed. Laser Surgery 29(6), 365–381 (2011).
Notes for 10 Full Body Red Light Studies
1) Novothor study 1
Ghigiarelli JJ, Fulop AM, Burke AA, Ferrara AJ, Sell KM, Gonzalez AM, Pelton LM, Zimmerman JA, Coke SG, Marshall DG. The Effects of Whole-Body Photobiomodulation Light-Bed Therapy on Creatine Kinase and Salivary Interleukin-6 in a Sample of Trained Males: A Randomized, Crossover Study. Front Sports Act Living. 2020 Apr 29;2:48
TIME: 15 minutes
Dosage: 25 J/cm^2
Irradiance 28 mW/cm^2
No improvement
----
2) Novothor Study 2
Navarro-Ledesma S, Carroll J, González-Muñoz A, Pruimboom L, Burton P. Changes in Circadian Variations in Blood Pressure, Pain Pressure Threshold and the Elasticity of Tissue after a Whole-Body Photobiomodulation Treatment in Patients with Fibromyalgia: A Tripled-Blinded Randomized Clinical Trial. Biomedicines. 2022 Oct 23;10(11):2678.
Whole-body PBM decreases pain and improves the quality of life in those suffering from FM. Furthermore, psychological factors such as kinesiophobia and self-efficacy are also improved.
6 month Followup
Navarro-Ledesma S, Carroll JD, González-Muñoz A, Burton P. Outcomes of whole-body photobiomodulation on pain, quality of life, leisure physical activity, pain catastrophizing, kinesiophobia, and self-efficacy: a prospective randomized triple-blinded clinical trial with 6 months of follow-up. Front Neurosci. 2024 Jan 31;18:1264821.
Both 3x a week for four weeks
Dosage: 33.6 J/cm^2
Note: Incorrect Dose listed
----
Novothor Study - Feasibility
Fitzmaurice B, Heneghan NR, Rayen A, Soundy A. Whole-body photobiomodulation therapy for chronic pain: a protocol for a feasibility trial. BMJ Open. 2022 Jun 29;12(6):e060058.
Both 3x a week for six weeks
Session 1=6 min.
Session 2=12 min.
Sessions 3–18=20 min.
Timescale: 3 treatments/week for 6 weeks.
Dosage: 33.6 J/cm^2
3) ***Feasibility - Actual Study 3**
Fitzmaurice BC, Heneghan NR, Rayen ATA, Grenfell RL, Soundy AA. Whole-Body Photobiomodulation Therapy for Fibromyalgia: A Feasibility Trial. Behav Sci (Basel). 2023 Aug 29;13(9):717.
Session 1=6 min.
Session 2=12 min.
Sessions 3–18=20 min.
Timescale: 3 treatments/week for 6 weeks.
Irradiance 28 mW/cm^2
Time 20 Minutes
Dose 33.6 J/cm^2
19 people completed the trial with improvements in many symptoms of Fibromyalgia.
---
4) Novothor Study 4
Rentz LE, Bryner RW, Ramadan J, Rezai A, Galster SM. Full-Body Photobiomodulation Therapy Is Associated with Reduced Sleep Durations and Augmented Cardiorespiratory Indicators of Recovery. Sports (Basel). 2022 Jul 31;10(8):119.
On days the the PBMT was used, there was 40 minutes reduced sleep, reduced heart rate while sleeping, and increased HRV during sleep.
Irradiance 28
20 minutes = 33.6 J/cm^2
2x a week
----
5) Novothor Study 5
Bowen R, Arany PR. Use of either transcranial or whole-body photobiomodulation treatments improves COVID-19 brain fog. J Biophotonics. 2023 Aug;16(8):e202200391.
14 minutes
28 mW/cm^2
Dose 23.5 J/cm^2
Participants showed improvement in their symptoms, performing slightly better than a separate group that used a transcranial PBM helmet.
----
6) Novothor Study 6
Forsey JD, Merrigan JJ, Stone JD, Stephenson MD, Ramadan J, Galster SM, Bryner RW, Hagen JA. Whole-body photobiomodulation improves post-exercise recovery but does not affect performance or physiological response during maximal anaerobic cycling. Lasers Med Sci. 2023 Apr 26;38(1):111
However, wbPBM elicited the ability to work at a higher heart rate throughout testing and seemed to enhance recovery through improved HRV the following morning.
Irradiance 28 mW/cm^2
Time 20 minutes before
Dose per session 33.6 J/cm^2
------
Non Novothor
7) Study 7
Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014;32(2):93-100.
Group 1: 42.8mW/cm^2 for 20 min and 51.4 J/cm^2 dose.
Group 2: 54.8mW/cm^2 for 15 min and 49.3 J/cm^2 dose.
Group 3: 10.3mW/cm^2 for 25 min and 15.5 J/cm^2 dose.
Group 4: 23.4mW/cm^2 for 12 min and 16.8 J/cm^2 dose.
All groups seemed to show a similar improvement in skin features.
Treatments were twice a week for 30 total treatments (15 week study).
Average Irradiance = 32.8 mW/cm^2
Average Dose = 33.25
----
8) Study 8
658nm Red LED light therapy for 30 min and 30 J/cm^2
Calculated intensity is 16.6 mW/cm^2.
Used to improve sleep and athletic recovery for 14 consecutive days including athletic training.
Zhao J, Tian Y, Nie J, Xu J, Liu D. Red light and the sleep quality and endurance performance of Chinese female basketball players. J Athl Train. 2012;47(6):673-678.
----
9) Study 9 - Lightstim
Z. Marcinkevics, Dz. Briljonoks, H. Kronberga, and J. Spigulis "LED-bed therapy of cardiovascular disorders: a volunteer study", Proc. SPIE 11221, Mechanisms of Photobiomodulation Therapy XV, 112210R (11 March 2020);
In a recent online PBM summit, it is revealed that LightStim emits 13.05 mW/cm^2. [4]
This means we can calculate the dose of 23.49 J/cm^2 for 30 minutes.
No effects EXCEPT reduced blood pressure suspected from thermal emissions
---
10) Study 10 - NO EFFECT - JOOV
Zagatto AM, Dutra YM, Lira FS, Antunes BM, Faustini JB, Malta ES, Lopes VHF, de Poli RAB, Brisola GMP, Dos Santos GV, Rodrigues FM, Ferraresi C. Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodul Photomed Laser Surg. 2020 Dec;38(12):766-772
Treatment time was only 5 minuites (2.5 min front and back).
Intensity was 46.17 mW/cm^2 and dose was 6.9 J/cm^2.
----
Successful Studies
Irradiance = (28+ 28 + 28 + 28 + 28 + 32.8 + 16.6)/7
= 27 mW/cm^2 Average
Dose = (33.6 + 33.6 + 33.6 + 23.5 + 33.6 + 33.25 + 30)/7
= 31.6 J/cm^2 Average
All studies including those with with no result
Irradiance = (28 + 28 + 28 + 28 + 28 + 28 + 32.8 + 16.6 + 13.05 + 46.17)/10
= 27.66 mW/cm^2 Average
Dose = (25 + 33.6 + 33.6 + 33.6 + 23.5 + 33.6 + 33.25 + 30 + 23.49 + 6.9)/10
= 27.65 J/cm^2 Average
1) Novothor study 1
Ghigiarelli JJ, Fulop AM, Burke AA, Ferrara AJ, Sell KM, Gonzalez AM, Pelton LM, Zimmerman JA, Coke SG, Marshall DG. The Effects of Whole-Body Photobiomodulation Light-Bed Therapy on Creatine Kinase and Salivary Interleukin-6 in a Sample of Trained Males: A Randomized, Crossover Study. Front Sports Act Living. 2020 Apr 29;2:48
TIME: 15 minutes
Dosage: 25 J/cm^2
Irradiance 28 mW/cm^2
No improvement
----
2) Novothor Study 2
Navarro-Ledesma S, Carroll J, González-Muñoz A, Pruimboom L, Burton P. Changes in Circadian Variations in Blood Pressure, Pain Pressure Threshold and the Elasticity of Tissue after a Whole-Body Photobiomodulation Treatment in Patients with Fibromyalgia: A Tripled-Blinded Randomized Clinical Trial. Biomedicines. 2022 Oct 23;10(11):2678.
Whole-body PBM decreases pain and improves the quality of life in those suffering from FM. Furthermore, psychological factors such as kinesiophobia and self-efficacy are also improved.
6 month Followup
Navarro-Ledesma S, Carroll JD, González-Muñoz A, Burton P. Outcomes of whole-body photobiomodulation on pain, quality of life, leisure physical activity, pain catastrophizing, kinesiophobia, and self-efficacy: a prospective randomized triple-blinded clinical trial with 6 months of follow-up. Front Neurosci. 2024 Jan 31;18:1264821.
Both 3x a week for four weeks
Dosage: 33.6 J/cm^2
Note: Incorrect Dose listed
----
Novothor Study - Feasibility
Fitzmaurice B, Heneghan NR, Rayen A, Soundy A. Whole-body photobiomodulation therapy for chronic pain: a protocol for a feasibility trial. BMJ Open. 2022 Jun 29;12(6):e060058.
Both 3x a week for six weeks
Session 1=6 min.
Session 2=12 min.
Sessions 3–18=20 min.
Timescale: 3 treatments/week for 6 weeks.
Dosage: 33.6 J/cm^2
3) ***Feasibility - Actual Study 3**
Fitzmaurice BC, Heneghan NR, Rayen ATA, Grenfell RL, Soundy AA. Whole-Body Photobiomodulation Therapy for Fibromyalgia: A Feasibility Trial. Behav Sci (Basel). 2023 Aug 29;13(9):717.
Session 1=6 min.
Session 2=12 min.
Sessions 3–18=20 min.
Timescale: 3 treatments/week for 6 weeks.
Irradiance 28 mW/cm^2
Time 20 Minutes
Dose 33.6 J/cm^2
19 people completed the trial with improvements in many symptoms of Fibromyalgia.
---
4) Novothor Study 4
Rentz LE, Bryner RW, Ramadan J, Rezai A, Galster SM. Full-Body Photobiomodulation Therapy Is Associated with Reduced Sleep Durations and Augmented Cardiorespiratory Indicators of Recovery. Sports (Basel). 2022 Jul 31;10(8):119.
On days the the PBMT was used, there was 40 minutes reduced sleep, reduced heart rate while sleeping, and increased HRV during sleep.
Irradiance 28
20 minutes = 33.6 J/cm^2
2x a week
----
5) Novothor Study 5
Bowen R, Arany PR. Use of either transcranial or whole-body photobiomodulation treatments improves COVID-19 brain fog. J Biophotonics. 2023 Aug;16(8):e202200391.
14 minutes
28 mW/cm^2
Dose 23.5 J/cm^2
Participants showed improvement in their symptoms, performing slightly better than a separate group that used a transcranial PBM helmet.
----
6) Novothor Study 6
Forsey JD, Merrigan JJ, Stone JD, Stephenson MD, Ramadan J, Galster SM, Bryner RW, Hagen JA. Whole-body photobiomodulation improves post-exercise recovery but does not affect performance or physiological response during maximal anaerobic cycling. Lasers Med Sci. 2023 Apr 26;38(1):111
However, wbPBM elicited the ability to work at a higher heart rate throughout testing and seemed to enhance recovery through improved HRV the following morning.
Irradiance 28 mW/cm^2
Time 20 minutes before
Dose per session 33.6 J/cm^2
------
Non Novothor
7) Study 7
Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014;32(2):93-100.
Group 1: 42.8mW/cm^2 for 20 min and 51.4 J/cm^2 dose.
Group 2: 54.8mW/cm^2 for 15 min and 49.3 J/cm^2 dose.
Group 3: 10.3mW/cm^2 for 25 min and 15.5 J/cm^2 dose.
Group 4: 23.4mW/cm^2 for 12 min and 16.8 J/cm^2 dose.
All groups seemed to show a similar improvement in skin features.
Treatments were twice a week for 30 total treatments (15 week study).
Average Irradiance = 32.8 mW/cm^2
Average Dose = 33.25
----
8) Study 8
658nm Red LED light therapy for 30 min and 30 J/cm^2
Calculated intensity is 16.6 mW/cm^2.
Used to improve sleep and athletic recovery for 14 consecutive days including athletic training.
Zhao J, Tian Y, Nie J, Xu J, Liu D. Red light and the sleep quality and endurance performance of Chinese female basketball players. J Athl Train. 2012;47(6):673-678.
----
9) Study 9 - Lightstim
Z. Marcinkevics, Dz. Briljonoks, H. Kronberga, and J. Spigulis "LED-bed therapy of cardiovascular disorders: a volunteer study", Proc. SPIE 11221, Mechanisms of Photobiomodulation Therapy XV, 112210R (11 March 2020);
In a recent online PBM summit, it is revealed that LightStim emits 13.05 mW/cm^2. [4]
This means we can calculate the dose of 23.49 J/cm^2 for 30 minutes.
No effects EXCEPT reduced blood pressure suspected from thermal emissions
---
10) Study 10 - NO EFFECT - JOOV
Zagatto AM, Dutra YM, Lira FS, Antunes BM, Faustini JB, Malta ES, Lopes VHF, de Poli RAB, Brisola GMP, Dos Santos GV, Rodrigues FM, Ferraresi C. Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodul Photomed Laser Surg. 2020 Dec;38(12):766-772
Treatment time was only 5 minuites (2.5 min front and back).
Intensity was 46.17 mW/cm^2 and dose was 6.9 J/cm^2.
----
Successful Studies
Irradiance = (28+ 28 + 28 + 28 + 28 + 32.8 + 16.6)/7
= 27 mW/cm^2 Average
Dose = (33.6 + 33.6 + 33.6 + 23.5 + 33.6 + 33.25 + 30)/7
= 31.6 J/cm^2 Average
All studies including those with with no result
Irradiance = (28 + 28 + 28 + 28 + 28 + 28 + 32.8 + 16.6 + 13.05 + 46.17)/10
= 27.66 mW/cm^2 Average
Dose = (25 + 33.6 + 33.6 + 33.6 + 23.5 + 33.6 + 33.25 + 30 + 23.49 + 6.9)/10
= 27.65 J/cm^2 Average
******END OF CHAPTER*****
NO MORE EDITING OR ILLUSTRATIONS PAST THIS POINT
NO MORE EDITING OR ILLUSTRATIONS PAST THIS POINT

If you did not follow that, don't worry, the gist of it is this: Solar meters are not designed to measure specific wavelengths of light rather their response curves are designed to give a fairly decent approximation of total irradiance for ALL the wavelengths of sunlight from around 300nm-1100nm together (the main output range from the sun).
If you want to measure SPECIFIC wavelengths you have to use a table of correction factors like shown here on the inside of the Sanwa laser power meter, but even that is only a rough approximation. If you are measuring a LED panel or bed with multiple wavelengths it gets even more inaccurate. This is why you can get twice or more the reported value and this is why all these power meters need correction factors based on the wavelength you need to measure. This measurement variation based on the calibration curve is likely the root cause of false-advertising of intensity in the Red Light Therapy industry (in addition to biases when companies measure their own equipment). And it seems nobody using solar meters to measure irradiance is even making an attempt to use the correction tables! The reason this is such a problem is again companies use higher irradiance numbers as a marketing gimmick on their comparison charts.
The Ten Full Body Red Light Therapy Studies Referenced in the Chart Above
1) Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014;32(2):93-100.
2) Zhao J, Tian Y, Nie J, Xu J, Liu D. Red light and the sleep quality and endurance performance of Chinese female basketball players. J Athl Train. 2012;47(6):673-678.
3) Z. Marcinkevics, Dz. Briljonoks, H. Kronberga, and J. Spigulis "LED-bed therapy of cardiovascular disorders: a volunteer study", Proc. SPIE 11221, Mechanisms of Photobiomodulation Therapy XV, 112210R (11 March 2020);
4) James Carroll Interview within the: "BRAIN + TRANSCRANIAL PHOTOBIOMODULATION THERAPY VIRTUAL SUMMIT"
https://brain-tpbmt.app.virtualsummits.com/
5) Zagatto AM, Dutra YM, Lira FS, Antunes BM, Faustini JB, Malta ES, Lopes VHF, de Poli RAB, Brisola GMP, Dos Santos GV, Rodrigues FM, Ferraresi C. Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodul Photomed Laser Surg. 2020 Dec;38(12):766-772.
6) Ghigiarelli JJ, Fulop AM, Burke AA, Ferrara AJ, Sell KM, Gonzalez AM, Pelton LM, Zimmerman JA, Coke SG, Marshall DG. The Effects of Whole-Body Photobiomodulation Light-Bed Therapy on Creatine Kinase and Salivary Interleukin-6 in a Sample of Trained Males: A Randomized, Crossover Study. Front Sports Act Living. 2020 Apr 29;2:48.
7) *Completed Trial Citation:
Navarro-Ledesma S, Carroll J, González-Muñoz A, Pruimboom L, Burton P. Changes in Circadian Variations in Blood Pressure, Pain Pressure Threshold and the Elasticity of Tissue after a Whole-Body Photobiomodulation Treatment in Patients with Fibromyalgia: A Tripled-Blinded Randomized Clinical Trial. Biomedicines. 2022 Oct 23;10(11):2678.
Navarro-Ledesma S, Gonzalez-Muñoz A, Carroll J, Burton P. Short- and long-term effects of whole-body photobiomodulation on pain, functionality, tissue quality, central sensitization and psychological factors in a population suffering from fibromyalgia: protocol for a triple-blinded randomized clinical trial. Therapeutic Advances in Chronic Disease. January 2022.
Navarro-Ledesma S, Carroll J, Burton P, Ana GM. Short-Term Effects of Whole-Body Photobiomodulation on Pain, Quality of Life and Psychological Factors in a Population Suffering from Fibromyalgia: A Triple-Blinded Randomised Clinical Trial. Pain Ther. 2023 Feb;12(1):225-239
8) Fitzmaurice B, Heneghan NR, Rayen A, Soundy A. Whole-body photobiomodulation therapy for chronic pain: a protocol for a feasibility trial. BMJ Open. 2022 Jun 29;12(6):e060058.
9) Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014 Feb;32(2):93-100.
10) Rentz LE, Bryner RW, Ramadan J, Rezai A, Galster SM. Full-Body Photobiomodulation Therapy Is Associated with Reduced Sleep Durations and Augmented Cardiorespiratory Indicators of Recovery. Sports (Basel). 2022 Jul 31;10(8):119.
If you want to measure SPECIFIC wavelengths you have to use a table of correction factors like shown here on the inside of the Sanwa laser power meter, but even that is only a rough approximation. If you are measuring a LED panel or bed with multiple wavelengths it gets even more inaccurate. This is why you can get twice or more the reported value and this is why all these power meters need correction factors based on the wavelength you need to measure. This measurement variation based on the calibration curve is likely the root cause of false-advertising of intensity in the Red Light Therapy industry (in addition to biases when companies measure their own equipment). And it seems nobody using solar meters to measure irradiance is even making an attempt to use the correction tables! The reason this is such a problem is again companies use higher irradiance numbers as a marketing gimmick on their comparison charts.
The Ten Full Body Red Light Therapy Studies Referenced in the Chart Above
1) Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014;32(2):93-100.
2) Zhao J, Tian Y, Nie J, Xu J, Liu D. Red light and the sleep quality and endurance performance of Chinese female basketball players. J Athl Train. 2012;47(6):673-678.
3) Z. Marcinkevics, Dz. Briljonoks, H. Kronberga, and J. Spigulis "LED-bed therapy of cardiovascular disorders: a volunteer study", Proc. SPIE 11221, Mechanisms of Photobiomodulation Therapy XV, 112210R (11 March 2020);
4) James Carroll Interview within the: "BRAIN + TRANSCRANIAL PHOTOBIOMODULATION THERAPY VIRTUAL SUMMIT"
https://brain-tpbmt.app.virtualsummits.com/
5) Zagatto AM, Dutra YM, Lira FS, Antunes BM, Faustini JB, Malta ES, Lopes VHF, de Poli RAB, Brisola GMP, Dos Santos GV, Rodrigues FM, Ferraresi C. Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodul Photomed Laser Surg. 2020 Dec;38(12):766-772.
6) Ghigiarelli JJ, Fulop AM, Burke AA, Ferrara AJ, Sell KM, Gonzalez AM, Pelton LM, Zimmerman JA, Coke SG, Marshall DG. The Effects of Whole-Body Photobiomodulation Light-Bed Therapy on Creatine Kinase and Salivary Interleukin-6 in a Sample of Trained Males: A Randomized, Crossover Study. Front Sports Act Living. 2020 Apr 29;2:48.
7) *Completed Trial Citation:
Navarro-Ledesma S, Carroll J, González-Muñoz A, Pruimboom L, Burton P. Changes in Circadian Variations in Blood Pressure, Pain Pressure Threshold and the Elasticity of Tissue after a Whole-Body Photobiomodulation Treatment in Patients with Fibromyalgia: A Tripled-Blinded Randomized Clinical Trial. Biomedicines. 2022 Oct 23;10(11):2678.
Navarro-Ledesma S, Gonzalez-Muñoz A, Carroll J, Burton P. Short- and long-term effects of whole-body photobiomodulation on pain, functionality, tissue quality, central sensitization and psychological factors in a population suffering from fibromyalgia: protocol for a triple-blinded randomized clinical trial. Therapeutic Advances in Chronic Disease. January 2022.
Navarro-Ledesma S, Carroll J, Burton P, Ana GM. Short-Term Effects of Whole-Body Photobiomodulation on Pain, Quality of Life and Psychological Factors in a Population Suffering from Fibromyalgia: A Triple-Blinded Randomised Clinical Trial. Pain Ther. 2023 Feb;12(1):225-239
8) Fitzmaurice B, Heneghan NR, Rayen A, Soundy A. Whole-body photobiomodulation therapy for chronic pain: a protocol for a feasibility trial. BMJ Open. 2022 Jun 29;12(6):e060058.
9) Wunsch A, Matuschka K. A controlled trial to determine the efficacy of red and near-infrared light treatment in patient satisfaction, reduction of fine lines, wrinkles, skin roughness, and intradermal collagen density increase. Photomed Laser Surg. 2014 Feb;32(2):93-100.
10) Rentz LE, Bryner RW, Ramadan J, Rezai A, Galster SM. Full-Body Photobiomodulation Therapy Is Associated with Reduced Sleep Durations and Augmented Cardiorespiratory Indicators of Recovery. Sports (Basel). 2022 Jul 31;10(8):119.

Average Body Depth
We want to know the irradiance of light where it meets the skin.
This would be on the surface of a full body bed and roughly a foot above the bed
This chart is for maximal depth but when you
24.5-34.5 (9.6-13.58 inches)
26-38 (10.2-15 inches
According to DIN 33402-2, all of the data refers to adults between the ages of 18 and 65 in Germany. The data was taken from the “Kleine Ergonomische Datensammlung" published by the Federal Institute for Occupational Safety and Health (BAuA). (Information without guarantee.)
We want to know the irradiance of light where it meets the skin.
This would be on the surface of a full body bed and roughly a foot above the bed
This chart is for maximal depth but when you
24.5-34.5 (9.6-13.58 inches)
26-38 (10.2-15 inches
According to DIN 33402-2, all of the data refers to adults between the ages of 18 and 65 in Germany. The data was taken from the “Kleine Ergonomische Datensammlung" published by the Federal Institute for Occupational Safety and Health (BAuA). (Information without guarantee.)

Insolation (Area at Right Angles) and Reflection issues
A. Insolation - Not only do you want a large area and a strong enough irradiance, you ideally want the application to be directly on the skin or having incoming photons at right angles. The ONLY way to get a true full body treatment is a 360 degree "wrap around" using a red light bed! **Think Solar Panels**
Reflection and Transmittance based on Angle
In aeronautics we talk about the Angle of Attack when determining the lift from a wind vector to the wing of an airplane. With red light therapy we might consider the angle that the light makes contact with our skin.
A. Insolation - Not only do you want a large area and a strong enough irradiance, you ideally want the application to be directly on the skin or having incoming photons at right angles. The ONLY way to get a true full body treatment is a 360 degree "wrap around" using a red light bed! **Think Solar Panels**
Reflection and Transmittance based on Angle
In aeronautics we talk about the Angle of Attack when determining the lift from a wind vector to the wing of an airplane. With red light therapy we might consider the angle that the light makes contact with our skin.

IV. Reflection issues
B. Minimizing Diffuse Reflection - Need panels close on skin!
Just as important as intensity, time, dose, and repetition - researchers understand there is a significant difference between skin contact treatment versus non-contact treatment. In fact, there is massive debate and inconclusive evidence about the “best” parameters in terms of wavelengths (nm), dose (J/cm^2), or intensity (mW/cm^2) for different conditions. Astonishingly, the only treatment parameter that is well-settled in the science – is that skin contact is the ideal way to administer red light therapy.
Bias Towards Non-Contact Treatment:
Unfortunately, the new generation of red light therapy “experts” have been biased by non-contact LED panels advertised to be used 6 inches away. They all conveniently overlooked the differences between skin contact and non-contact delivery while they wrote their original books and blogs with their affiliate promotions.
You might think that 6 inches is some magical clinically-studied treatment number since that is what everyone talks about. But you would be surprised that there are practically NO studies referencing 6 inches! In fact looking through pub med, I only found ONE STUDY and the results were basically NO EFFECT!! All positive studies with red light therapy and low level laser are ALL DIRECT CONTACT!!
There are multiple reasons for this the main one being reflection! So standing any significant distance away from a red light panel will result massive losses due to skin reflection alone!
The NIST database of skin reflectance spectrum measurements shows a skin reflectance on average of about 60% in white skin around 660nm to 850nm! This is very high! Other references which corroborate the high average reflection estimate of 60% include:
1. The evolution of human skin color measured reflectance at 685nm in Northern Latitudes at about 65%! [2]
2. Another reflectance measurements of human skin study showed a very similar spectrum as the NIST data. [3]
3. Researchers used a camera technique to measure reflection spectrum and found about 60% reflection (and increasing) in the Red range. [4]
4. Spectral Reflection study of facial skin of 241 participants showed an average reflectance of 60% in the red range and clearly increasing reflectance towards NIR. [5]
5. In one review the authors mention how 4-7% of most wavelengths pass through the first layer of skin, but through internal reflection and scattering, light will exit the body through what is called remittance. Their remittance spectrum shows similar to the NIST data, with Caucasion skin having over 60% remittance between 600nm to 900nm. [6]
So ALL 5 of these references match very well, no matter what year they were studied, including the NIST data makes 6 well studied skin reflection metrics. Despite what some authors might say otherwise.
60% reflection is a tremendous amount of intensity losses! Lets say you have a panel that you THINK emits 100mW/cm^2 at 6 inches. Well actually they lied about intensity and it is about 45mW/cm^2 at 6 inches. Then 60% of that gets reflected away so you are left with an effective intensity of 18 mW/cm^2. Is that what you paid for?
Most panel companies don’t tell you about skin reflection because they don't want their customers to realize they are using an inefficient and mostly unscientific dosing method by being 6+ inches away. And some delusional brands and self-proclaimed experts may not even be aware of this issue, so I do presume to blame them for their misinformation.
Example
In the first-ever study using a top name brand LED Panel [their most powerful] system had athletes use the panels at 12 inches away for 5 minutes. Based on their calculations with skin contact dosage in earlier studies, the authors thought 5 minutes would be plenty sufficient for a clinical benefit. But they found no significant improvement in the treatment group. [7]
The above studies show what happens when companies don’t educate the market about the skin reflection issue. It hurts the science and customers might not get the results that they expect then they stand 6+ inches away from a panel.
[1] NIST Skin Reflection Data
https://www.nist.gov/programs-projects/reflectance-measurements-human-skin
Raw Data: https://opendata.nist.gov/1832_Data_JResNIST_skinrefl%20v3.txt
[2] Evolution of Human Skin Coloration.
Nina G. Jablonski and George Chaplin
Department of Anthropology, California Academy of Sciences, Golden Gate Park,
San Francisco, CA
https://anth.la.psu.edu/research/research-labs/jablonski-lab/research/JablonskiLabskin.pdf
[3] Cooksey, Catherine & Allen, David. (2013). Reflectance measurements of human skin from the ultraviolet to the shortwave infrared (250 nm to 2500 nm). Proceedings of SPIE - The International Society for Optical Engineering. 8734. 87340N. 10.1117/12.2015821.
https://www.researchgate.net/publication/269325503_Reflectance_measurements_of_human_skin_from_the_ultraviolet_to_the_shortwave_infrared_250_nm_to_2500_nm
[4] Validation of a Method to Estimate Skin Spectral Reflectance Using a Digital Camera.
Christopher Thorstenson
Rochester Institute of Technology
RIT Scholar Works
5-9-2017
https://scholarworks.rit.edu/cgi/viewcontent.cgi?article=10602&context=theses
[5] Koran A, Powers JM, Raptis CN, Yu R. Reflection spectrophotometry of facial skin. J Dent Res. 1981 Jun;60(6):979-82. doi: 10.1177/00220345810600061301. PMID: 6939721.
https://pubmed.ncbi.nlm.nih.gov/6939721/
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/67548/10.1177_00220345810600061301.pdf
[6] Anderson RR, Parrish JA. The optics of human skin. J Invest Dermatol. 1981 Jul;77(1):13-9. doi: 10.1111/1523-1747.ep12479191. PMID: 7252245.
[7} Zagatto, Alessandro & Dutra, Yago & Lira, Fabio & Antunes, Barbara & Bombini Faustini, Júlia & Malta, Elvis & Fialho Lopes, Vithor & de Poli, Rodrigo & Brisola, Gabriel & dos Santos, Giovanny Viegas & Rodrigues, Fabio & Ferraresi, Cleber. (2020). Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodulation Photomedicine and Laser Surgery. 38. -. 10.1089/photob.2020.4803.
B. Minimizing Diffuse Reflection - Need panels close on skin!
Just as important as intensity, time, dose, and repetition - researchers understand there is a significant difference between skin contact treatment versus non-contact treatment. In fact, there is massive debate and inconclusive evidence about the “best” parameters in terms of wavelengths (nm), dose (J/cm^2), or intensity (mW/cm^2) for different conditions. Astonishingly, the only treatment parameter that is well-settled in the science – is that skin contact is the ideal way to administer red light therapy.
Bias Towards Non-Contact Treatment:
Unfortunately, the new generation of red light therapy “experts” have been biased by non-contact LED panels advertised to be used 6 inches away. They all conveniently overlooked the differences between skin contact and non-contact delivery while they wrote their original books and blogs with their affiliate promotions.
You might think that 6 inches is some magical clinically-studied treatment number since that is what everyone talks about. But you would be surprised that there are practically NO studies referencing 6 inches! In fact looking through pub med, I only found ONE STUDY and the results were basically NO EFFECT!! All positive studies with red light therapy and low level laser are ALL DIRECT CONTACT!!
There are multiple reasons for this the main one being reflection! So standing any significant distance away from a red light panel will result massive losses due to skin reflection alone!
The NIST database of skin reflectance spectrum measurements shows a skin reflectance on average of about 60% in white skin around 660nm to 850nm! This is very high! Other references which corroborate the high average reflection estimate of 60% include:
1. The evolution of human skin color measured reflectance at 685nm in Northern Latitudes at about 65%! [2]
2. Another reflectance measurements of human skin study showed a very similar spectrum as the NIST data. [3]
3. Researchers used a camera technique to measure reflection spectrum and found about 60% reflection (and increasing) in the Red range. [4]
4. Spectral Reflection study of facial skin of 241 participants showed an average reflectance of 60% in the red range and clearly increasing reflectance towards NIR. [5]
5. In one review the authors mention how 4-7% of most wavelengths pass through the first layer of skin, but through internal reflection and scattering, light will exit the body through what is called remittance. Their remittance spectrum shows similar to the NIST data, with Caucasion skin having over 60% remittance between 600nm to 900nm. [6]
So ALL 5 of these references match very well, no matter what year they were studied, including the NIST data makes 6 well studied skin reflection metrics. Despite what some authors might say otherwise.
60% reflection is a tremendous amount of intensity losses! Lets say you have a panel that you THINK emits 100mW/cm^2 at 6 inches. Well actually they lied about intensity and it is about 45mW/cm^2 at 6 inches. Then 60% of that gets reflected away so you are left with an effective intensity of 18 mW/cm^2. Is that what you paid for?
Most panel companies don’t tell you about skin reflection because they don't want their customers to realize they are using an inefficient and mostly unscientific dosing method by being 6+ inches away. And some delusional brands and self-proclaimed experts may not even be aware of this issue, so I do presume to blame them for their misinformation.
Example
In the first-ever study using a top name brand LED Panel [their most powerful] system had athletes use the panels at 12 inches away for 5 minutes. Based on their calculations with skin contact dosage in earlier studies, the authors thought 5 minutes would be plenty sufficient for a clinical benefit. But they found no significant improvement in the treatment group. [7]
The above studies show what happens when companies don’t educate the market about the skin reflection issue. It hurts the science and customers might not get the results that they expect then they stand 6+ inches away from a panel.
[1] NIST Skin Reflection Data
https://www.nist.gov/programs-projects/reflectance-measurements-human-skin
Raw Data: https://opendata.nist.gov/1832_Data_JResNIST_skinrefl%20v3.txt
[2] Evolution of Human Skin Coloration.
Nina G. Jablonski and George Chaplin
Department of Anthropology, California Academy of Sciences, Golden Gate Park,
San Francisco, CA
https://anth.la.psu.edu/research/research-labs/jablonski-lab/research/JablonskiLabskin.pdf
[3] Cooksey, Catherine & Allen, David. (2013). Reflectance measurements of human skin from the ultraviolet to the shortwave infrared (250 nm to 2500 nm). Proceedings of SPIE - The International Society for Optical Engineering. 8734. 87340N. 10.1117/12.2015821.
https://www.researchgate.net/publication/269325503_Reflectance_measurements_of_human_skin_from_the_ultraviolet_to_the_shortwave_infrared_250_nm_to_2500_nm
[4] Validation of a Method to Estimate Skin Spectral Reflectance Using a Digital Camera.
Christopher Thorstenson
Rochester Institute of Technology
RIT Scholar Works
5-9-2017
https://scholarworks.rit.edu/cgi/viewcontent.cgi?article=10602&context=theses
[5] Koran A, Powers JM, Raptis CN, Yu R. Reflection spectrophotometry of facial skin. J Dent Res. 1981 Jun;60(6):979-82. doi: 10.1177/00220345810600061301. PMID: 6939721.
https://pubmed.ncbi.nlm.nih.gov/6939721/
https://deepblue.lib.umich.edu/bitstream/handle/2027.42/67548/10.1177_00220345810600061301.pdf
[6] Anderson RR, Parrish JA. The optics of human skin. J Invest Dermatol. 1981 Jul;77(1):13-9. doi: 10.1111/1523-1747.ep12479191. PMID: 7252245.
[7} Zagatto, Alessandro & Dutra, Yago & Lira, Fabio & Antunes, Barbara & Bombini Faustini, Júlia & Malta, Elvis & Fialho Lopes, Vithor & de Poli, Rodrigo & Brisola, Gabriel & dos Santos, Giovanny Viegas & Rodrigues, Fabio & Ferraresi, Cleber. (2020). Full Body Photobiomodulation Therapy to Induce Faster Muscle Recovery in Water Polo Athletes: Preliminary Results. Photobiomodulation Photomedicine and Laser Surgery. 38. -. 10.1089/photob.2020.4803.
I. Wavelength Medicine - Penetration and therapeutic value
II. Fluence & Dosage (J/cm^2) = Irradiance x Time
III. Visits per week (2x a day).
Dosage is important need the right amount of intensity with the right amount of time.
Like cooking a turkey.
If a doctor tells you to take 2 antibiotic pills every 2 hours 8x a day = 16 pills total.
Clearly there is a difference between taking 16 pills all at once vs 1 pill every hour even though the daily dosage is the same!
Application/Treatment/Dosage - Transmission (Intensity, Frequency Spectra, and Dose)
Reception/Absorption/Biological Healing Effects and benefits from EFFECTIVE application... chromophores shine, mito shines, cells shine, tissues shine, body shines!!
Red light therapy is a whole body illumination device. You glow from molecules to organelles, to cells to tissues to organs to organism!
Introduce Quantum Body and New Science
Energy APPLIED - Application (science of applied red light with correct area, intensity and frequency spectra
Energy RECEIVED - Absorption and Transduction - Mechanisms of healing benefits of the applied effective treatment (more energy, better circulation, reduced inflammation, increased stem cells, etc.
Reciprocity.
**Benefits with signaling , drop a pebble in a pond.
II. Fluence & Dosage (J/cm^2) = Irradiance x Time
III. Visits per week (2x a day).
Dosage is important need the right amount of intensity with the right amount of time.
Like cooking a turkey.
If a doctor tells you to take 2 antibiotic pills every 2 hours 8x a day = 16 pills total.
Clearly there is a difference between taking 16 pills all at once vs 1 pill every hour even though the daily dosage is the same!
Application/Treatment/Dosage - Transmission (Intensity, Frequency Spectra, and Dose)
Reception/Absorption/Biological Healing Effects and benefits from EFFECTIVE application... chromophores shine, mito shines, cells shine, tissues shine, body shines!!
Red light therapy is a whole body illumination device. You glow from molecules to organelles, to cells to tissues to organs to organism!
Introduce Quantum Body and New Science
Energy APPLIED - Application (science of applied red light with correct area, intensity and frequency spectra
Energy RECEIVED - Absorption and Transduction - Mechanisms of healing benefits of the applied effective treatment (more energy, better circulation, reduced inflammation, increased stem cells, etc.
Reciprocity.
**Benefits with signaling , drop a pebble in a pond.
Heating Effects -

Reviewing what we introduced in chapter 4, there are Four Types of Watts commonly discussed in Red Light Therapy (maybe more)! Not just one. Hence there is a lot of confusing around power ratings in red light therapy devices!!
1) Rated Watts: The maximum electrical power rating for all of the LEDs. This will be in the user manual.
2) Consumed or Actual Watts: The electrical power that is actually consumed by the device. The consumed watts are the amount of electricity consumed by the LED device which can be measured from a device like "Kill-a-watt". LEDs aren’t perfectly efficient (usually only 15% to 30% conversion from electricity to light), as well some electrical power is spent in the drivers and fans.
1) Rated Watts: The maximum electrical power rating for all of the LEDs. This will be in the user manual.
2) Consumed or Actual Watts: The electrical power that is actually consumed by the device. The consumed watts are the amount of electricity consumed by the LED device which can be measured from a device like "Kill-a-watt". LEDs aren’t perfectly efficient (usually only 15% to 30% conversion from electricity to light), as well some electrical power is spent in the drivers and fans.

3) Optical, Emitted, “Light”, or Radiant Watts: The total amount of radiant (optical) power emitted by the device. Where we may say Optical or Light as a general term even though the power can also be invisible Near-Infrared. Now it is getting interesting! More important than Rated or Consumed Watts, we need to know how many Watts of optical power is actually emitted from the device. To do this properly, usually companies need to send their panels to a 3rd party lab. Where they measure the panel inside an integrating sphere to measure the Total Watts output.
Total Optical Power Alone is what is therapeutically important (not rated or consumed), but it also very difficult or impossible to measure accurately without a lab. But luckily for full body light beds there is a way to estimate this number.
Total Optical Power for a full body light bed or panel!
The total optical power is the Irradiance multiply by the area covered. Irradiance tells you essentially how bright or energetic the light is at a point, while the total power tells you the TOTAL energy over the entire area applied. Here is where we really see the benefits of having a full body red light bed because your ENTIRE body will be covered versus a small area with local applicators and panels. So if we have an accurate irradiance reading we can simply multiply the average value by the total area. But what is the total area? Well, it is the surface area of your skin. More on this in Chapter 11!
Total Optical Power Alone is what is therapeutically important (not rated or consumed), but it also very difficult or impossible to measure accurately without a lab. But luckily for full body light beds there is a way to estimate this number.
Total Optical Power for a full body light bed or panel!
The total optical power is the Irradiance multiply by the area covered. Irradiance tells you essentially how bright or energetic the light is at a point, while the total power tells you the TOTAL energy over the entire area applied. Here is where we really see the benefits of having a full body red light bed because your ENTIRE body will be covered versus a small area with local applicators and panels. So if we have an accurate irradiance reading we can simply multiply the average value by the total area. But what is the total area? Well, it is the surface area of your skin. More on this in Chapter 11!

Area of Coverage and Penetration Depth
More Area = More Power = More Therapeutic Photons hitting your skin!
Depends on the size of the panel and intensity (called irradiance)
Coverage
Ideally you would want a full body bed or large full body panel. Larger spot size enables greater depth of penetration, for improved absorption of energy at the target tissue.
Clinically, this means that larger spot diameters can be achieved with larger red light panels than smaller for even a given wavelength and intensity. Not only does this mean quicker treatment times (due to the larger spot area on the skin surface) but, it has been shown, using Monte Carlo modelling, that larger spot diameters result in useful fluences deep within the skin.
https://link.springer.com/article/10.1007/s10103-017-2317-4
More Area = More Power = More Therapeutic Photons hitting your skin!
Depends on the size of the panel and intensity (called irradiance)
Coverage
Ideally you would want a full body bed or large full body panel. Larger spot size enables greater depth of penetration, for improved absorption of energy at the target tissue.
Clinically, this means that larger spot diameters can be achieved with larger red light panels than smaller for even a given wavelength and intensity. Not only does this mean quicker treatment times (due to the larger spot area on the skin surface) but, it has been shown, using Monte Carlo modelling, that larger spot diameters result in useful fluences deep within the skin.
https://link.springer.com/article/10.1007/s10103-017-2317-4

MORE IS NOT NECESSARILY BETTER
Unfortunately the red light therapy industry has gone down the wrong path. A very popular company heavily marketed their "clinical power LED" panels and became the standard for the industry. Unfortunately the high power of the LEDs requires users to stand at least 6 inches to avoid tissue heating, biphasic dose, and EMFs. At this distance the photon beam will be highly divergent and allow for reflection losses from the skin.
How many high-powered panels like this are used in Red Light Therapy, LLLT, and Photobiomodulation studies on Pubmed? ONLY ONE out of thousands!
So why is everyone so excited to use it? Marketing.
In reality, most studies are using lasers, LED arrays, and LED or laser clusters and mostly placing them in contact with the skin. In one review on the complexity of photobiomodulation parameters, it was simply put as "The first issue to be addressed is light reflection from the surface of the skin, which can be minimized if the optical probe is held in firm contact with the skin." [1]
Another study makes a specific note about their treatment protocol "placed in contact with the skin and firm pressure applied." [2]
We can not assume that skin reflectance is insignificant, given how many studies use the lasers or LEDs directly on the skin! The review article also includes that the "Application Technique" (contact or non-contact) should always be reported in studies because it is just as important as other parameters such as wavelength, intensity, and dosage. [6]
Unfortunately the red light therapy industry has gone down the wrong path. A very popular company heavily marketed their "clinical power LED" panels and became the standard for the industry. Unfortunately the high power of the LEDs requires users to stand at least 6 inches to avoid tissue heating, biphasic dose, and EMFs. At this distance the photon beam will be highly divergent and allow for reflection losses from the skin.
How many high-powered panels like this are used in Red Light Therapy, LLLT, and Photobiomodulation studies on Pubmed? ONLY ONE out of thousands!
So why is everyone so excited to use it? Marketing.
In reality, most studies are using lasers, LED arrays, and LED or laser clusters and mostly placing them in contact with the skin. In one review on the complexity of photobiomodulation parameters, it was simply put as "The first issue to be addressed is light reflection from the surface of the skin, which can be minimized if the optical probe is held in firm contact with the skin." [1]
Another study makes a specific note about their treatment protocol "placed in contact with the skin and firm pressure applied." [2]
We can not assume that skin reflectance is insignificant, given how many studies use the lasers or LEDs directly on the skin! The review article also includes that the "Application Technique" (contact or non-contact) should always be reported in studies because it is just as important as other parameters such as wavelength, intensity, and dosage. [6]

Since we evolved under the sun which emits anywhere from 20 to 40 mW/cm^2 in the Red and Near-Infrared range, it is likely a natural protection from overdose is having higher skin reflectance in this range.
Image below adapted from
Ohshiro T. The Proximal Priority Theory: An Updated Technique in Low Level Laser Therapy with an 830 nm GaAlAs Laser. Laser Ther. 2012
Image below adapted from
Ohshiro T. The Proximal Priority Theory: An Updated Technique in Low Level Laser Therapy with an 830 nm GaAlAs Laser. Laser Ther. 2012
Wavelength Doesn't Matter For Light Transmission?
This is potentially an industry-changing conclusion that bears quotation:
"Thus, it can be suggested that light therapy dosimetry targeting subcutaneous tissues deserve better attention at light attenuation due to different skin features rather than what wavelength to use (at the observed spectral range)" [6]
In layman's terms, the proper dose and depth penetration depends more on the skin composition and much less on wavelength than most people currently believe (as long as you are between 630nm to 905nm range). This is a big deal.
[6] Sabino, Caetano & Deana, A.M. & Silva, Daniela & França, Cristiane & Yoshimura, Tania & Ribeiro, Martha. (2015). Optical properties of mice skin for optical therapy relevant wavelengths: Influence of gender and pigmentation. Progress in Biomedical Optics and Imaging - Proceedings of SPIE. 9309. 10.1117/12.2080853.
This is potentially an industry-changing conclusion that bears quotation:
"Thus, it can be suggested that light therapy dosimetry targeting subcutaneous tissues deserve better attention at light attenuation due to different skin features rather than what wavelength to use (at the observed spectral range)" [6]
In layman's terms, the proper dose and depth penetration depends more on the skin composition and much less on wavelength than most people currently believe (as long as you are between 630nm to 905nm range). This is a big deal.
[6] Sabino, Caetano & Deana, A.M. & Silva, Daniela & França, Cristiane & Yoshimura, Tania & Ribeiro, Martha. (2015). Optical properties of mice skin for optical therapy relevant wavelengths: Influence of gender and pigmentation. Progress in Biomedical Optics and Imaging - Proceedings of SPIE. 9309. 10.1117/12.2080853.
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