The Ultimate Guide to Red Light Therapy: How to Use Red and Near-Infrared Light Therapy for Anti-Aging, Fat Loss, Muscle Gain, Performance Enhancement, and Brain Optimization

by Ari Whitten

How Deep Does Red/NIR Light Penetrate Into Our Body? The answer to this question is actually much more complex than you might imagine… The penetration depth differs depending on many factors: The type of tissues (e.g. skin vs. bone vs. fat vs. muscle). First, it depends on exactly what part of your body you shine it on. It will penetrate much more deeply into your belly than your skull. The power output of the device. More powerful lights can deliver more light to deeper tissues of the body. The distance of the device from your body. As explained previously, the closer the light is to your body, the higher the light intensity will be and the deeper it will penetrate.

The wavelengths of light. Blue light and UV light, for example, get almost completely blocked by the skin and do not penetrate much more deeply than the very surface layers of skin. Whereas red and near-infrared penetrate much more deeply. And within that category, near-infrared has significantly greater penetration depth than red light, and there are even some small differences between specific wavelengths of red and near-infrared light in terms of penetration depth.

Penetration depth “is defined as the depth at which the intensity of the radiation inside the material falls to 1/e (about 37%) of its original value at (or more properly, just beneath) the surface.”

Red and near-infrared light can penetrate several centimeters (close to 2 inches) into your body, and a high-power light with the right wavelengths (especially near-infrared) can even penetrate through the thick and dense human skull to deliver light directly into the brain.

Now that you understand the importance of the power density of the light, here’s the big problem with most lights on the market. Most devices being sold (that you might pay $100-$900 for) are: Grossly underpowered and simply too low wattage to reach therapeutic power densities of above 50mW/cm2 with large coverage of body areas. This is especially problematic for treating deep tissues. So you’d end up having to use the light for extended periods (sometimes upwards of 20-40 minutes) to generate an effect. Moreover, the weaker lights won’t penetrate deeply into the body and to even treat any deeper issues, even with extended exposure times. Very small, and thus, only treat a small area of your body. Even if a small light has optimal power density, a small light that radiates light on only 5-10 square inches will require multiple treatments to cover a significant portion of your body. (Note: This is a major limitation with small LED devices.)

If I can give one piece of advice on which light to get, it’s this: Get a high-power light that reaches therapeutic power outputs and is big enough to cover a significant portion of your body.

I will tell you right now that 99% of the red light therapy products being sold in major outlets online are a waste of money. So please be aware of the power output and size of the light you’re interested in. Not understanding those two factors caused me to waste a huge amount of money on ineffective and time-consuming lights.

Here’s why low-power devices and small devices are a problem (even if you were to increase the length of time you use it):

Penetration Depth:

But here’s the problem: More powerful lights penetrate more deeply into the body. They deliver more overall light deeper into the body.

If you want to treat deeper tissues below the skin, I strongly suggest getting a high-power device rather than a low power device.

Convenience: Don’t underestimate the simple power of being able to do an entire treatment in 1-5 minutes vs. having to do it for 10-40 minutes. A smaller and weaker light will require much longer sessions to treat a significant area (or areas) of your body.

For many people who are busy, this is the difference between actually making time to do it vs. just having another thing sitting in your garage unused because you don’t have the time.

Body area treated at once: This is a huge factor as well. The bigger more powerful devices allow you to do something very cool. They allow you to stand further back from the light (2 or 3 feet away) and still have enough power output to reach therapeutic levels. This allows the light to spread out and hit a much larger area of your body at once.

the power of the light and the distance from it also impacts the effectiveness of the dose.

total dose is not the only thing that matters—the power of the light and distance from the body also influence the end result.

In short, whether your primary objective is anti-aging skin treatments, fat loss, muscle gain, or to treat organs and glands, including the brain, high-power lights are the way to go. They allow you to do so much more and get numerous benefits, are more effective, and they can treat larger areas of the body at once, so they’re far more time-efficient.

Also note that if you get a pure near-infrared device, it will emit slightly higher outputs due to the LED bulbs themselves emitting more light output. If you were to measure a pure red light vs. a pure near-infrared light produced by the same company, the near-infrared device would have roughly 20-30% higher light output. Compared to a 50-50 mix of red and near-infrared LEDs, the pure near-infrared device would have roughly 10-20% higher light output. If you get a pure red light device, your light output numbers will be slightly lower, and if you get a pure near-infrared device, your light output numbers will be slightly higher.

IMPORTANT: The following recommendations are based on the lights I recommend. All these calculations change when you use lights that are less powerful than the ones I recommend. If you purchase a different light, you will need to measure the power density of that light at different distances and calculate doses for that specific light according to the guidelines in this book.

For general use, the light should be about 6-36 inches away from your body. Closer distances (6”-12” away from your body) are ideal for deep tissue treatments as you’ll get a higher dose and much greater depth of penetration.

Further distances (12”-36” away from your body) are ideal for treating surface skin issue...

Get a high-power light that can still deliver an effective dose from further distances. This allows you to treat much larger areas of your body at once compared to lower power lights.

Ideal frequency of use is likely between 3-7x/week (or up to once per day).

Start SLOW. This is especially true if you are in poor health. Do not immediately assume that “more is better” by using the high end of the range of doses. It’s not. It’s especially not true when first starting out with red and near-infrared light therapy, or if you are in poor health. If you are in poor health, start with the lowest possible doses and SLOWLY increase the dose from there in subsequent sessions. (If you are extremely ill or severely fatigued, you can even start with lower doses than the lowest end of my recommended ranges.) Also, giving a day or two between sessions is a good idea at first.

Be conservative with dosing for any sensitive areas.

For skin issues, we want between 3J to roughly 15J per area.

For deeper issues (e.g. muscle, bone, brain, organs, glands, fat, etc.), we want around 10-40J per area,

Total Treatment Dose/Time: I suggest that you limit total treatment dose for all areas of the body to no more than roughly 120J. So assuming the light is 6” or 12” away from your body, that means no more than 15-20 minutes of time total with light shining on your body.

With all these details and discussion of science, it’s easy to get overwhelmed and think that using one of these lights must be terribly complex. It isn’t. It’s actually very simple and straightforward: The basic idea is to just switch the light on and put your body in front of it. Okay, it’s a little more complicated than that, but really not much. The details to be aware of are: Optimizing power density/irradiance for the tissue you are treating by adjusting your distance from the light Getting the dose right Your body position Practical tips/strategies for specific goals

When choosing the right red and near-infrared light therapy light device, you want to select a device that’s long-lasting, has a great warranty, is well-manufactured, and most importantly, one that offers the correct wavelengths at the right power density over a large area.

The most important things to look for specifically include the red and near-infrared light therapy devices:

Wavelength: What wavelengths does the device offer? Do these have health benefits? Are they in the proven ranges of 600-700nm and 780-1070nm, or better, the most ...

Power Density: How much irradiance/power does the device deliver—what is the power density in mW/cm2? (To calculate this, you need to know the total wat...

Size of the light and treatment area: This is critically important—how big of an area will it treat? Is it a small light of less than 12” or a big light that can treat half of your body or your whole body all at once? Think about it: Do you want to hold one of these small devices by hand for 30-60 minutes to do a treatment? Probably not. You’ll get tired of using it pretty quickly. So it has to be convenient, and ideally, has to be something that is not only fast, but something that you d...

Warranty: How long does the warranty last? Will you have time to find out if it works? (Hint: look for...

What do you want it for? Depending on your specific purpose, there are a few different devices you may want to consider. (If you have specialty needs like brain health, or skin health, it will affect the wavelengths you w...

Wavelength and intensity makes all the difference between incredible benefits and no benefits.

Look for wavelengths in the proven therapeutic ranges. Based on the bulk of the research, you want: 630-680nm (the optimal healing spectrum of red light) 800 to 880nm (the optimal healing spectrum of near-infrared) or a combination of both

Also, when it comes to red vs. near-infrared, be aware that it doesn’t have to be one or the other!

I suggest thinking about long-term goals here and making a wise purchase. Get a device that is powerful, cost-effective, and efficient so you can conveniently do treatments for a large area of your body in just a few minutes. High-power lights are going to give you far more benefits in far less time, are more effective (especially for deep tissues), and have more flexibility in how you can use them.

I also strongly recommend getting a large panel light over a hand-held device. Most people who purchase the small devices end up never using them because it’s just too time consuming.

So then you might wonder, why distinguish between them at all? What differences—if any—exist between red and near-infrared light?

There are basically four differences to be aware of:

Red light is visible to the human eye, while near-infrared is almost entirely invisible.

Near-infrared (800-880nm) has significantly more power output per LED bulb.

Near-infrared can be more expensive, depending on who you purchase it from.

Near-infrared penetrates a little deeper into the tissues compared to red light (especially through the skull).

The most significant difference here worth noting is the penetration depth. It’s worth figuring out exactly what you intend to use the light for—either more surface treatments or treating deeper tissues.

That said, please keep in mind that both red and near-infrared light have the same effects on cells, and both essentially work for all purposes. Near-infrared