Deep Penetrating Light Therapy: Well-being from the Inside, Out

Woman getting red light therapy

Red light therapy benefits your entire body⁠—including skin, ligaments, muscles, and more⁠—but only if it can penetrate deep enough. To help your brain, for example, light has to travel through your skin, bone, and other tissue⁠. But not all light can travel that deep while still maintaining enough energy to have an effect. 

Think about covering a flashlight with your hand. Your skin might glow red if the light is powerful enough, but it won’t provide a ton of useful light in your room. 

Fortunately, after decades of research and analysis, scientists have uncovered exactly what kind of light will be most effective for therapy, even if you need to reach deep into the body. Here’s the short version: 

Longer wavelengths penetrate further into the body. 

In practical terms, that means you should mostly use red and near-infrared light. However, the exact wavelengths you should use varies depending on the conditions you want to treat. For example, skin cells benefit most from slightly shorter wavelength red light, while inner organs need near-infrared. 

In this article,  we’ll discuss what kind of light penetrates deepest into the body, and show you exactly which wavelengths we use in Platinum Therapy Lights, and why. But first, let’s quickly review how light, in general, affects the human body before getting more specific. 

man in sunlight

How Light Affects the Human Body

The effects of light on the human body are both direct (photochemical reactions within the tissues themselves) and indirect (signals generated by photoreceptor cells in the retina). Light affects our circadian rhythms and influences a host of biological reactions.

During light therapy, LED bulbs shine specific wavelengths of light onto the skin, where the light naturally stimulates the production of energy within cells. This leads to improved cellular functioning and regeneration. 

When light photons enter your body’s cells, amazing processes start to take place. Exactly what happens depends (again) on wavelengths. Some, like UV and blue wavelengths, have both positive and negative effects. Not much is known about green and yellow because these wavelengths have barely been studied. 

Since the penetration depth of UV and blue wavelengths is so shallow and their direct benefits are largely confined to the outer layers of skin, here we will only focus on the effects of deep penetrating light, including red and NIR wavelengths. These are the wavelengths with the greatest number of clinically proven benefits to the body and no known side effects.

When red/NIR light photons passing through the body’s tissues are picked up by photosensitive chromophores, the interaction stimulates increased energy production in mitochondria, which are the energy producers within cells. 

Increased cellular energy can have profound effects on the functionality of individual cells, which has a ripple effect on the body’s systems.

We all know that our bodies don’t perform well when we’re chronically stressed, exhausted, or when we’re ill or injured. These factors stress the body at a cellular level—especially when the stresses become chronic and lead to inflammation. Inflammation is one of the primary factors in poor cellular metabolism and according to Harvard researcher Dr. Michael Hamblin, red light reduces inflammation.  

Research has shown that mitochondrial dysfunction (reduced cellular metabolism, or low-energy cells) is a leading cause or contributor to many chronic conditions. A Cornell University study found that mitochondrial dysfunction is a major cause of neurodegenerative disorders such as Alzheimer’s and Parkinson’s. Reversing mitochondrial dysfunction may, therefore, help the body be more resilient to diseases and slow the aging process.

Deep penetrating red light therapy, which is also known as photobiomodulation (PBM), or low-level light therapy (LLLT) restores mitochondrial functioning, giving cells enough energy to perform their functions. This, in turn, can stimulate beneficial processes in the body and potentially support prescribed treatments for a variety of chronic conditions. 

Before we get into specific therapeutic wavelengths, let’s talk about light and how it absorbs into the skin so you get an idea of the mechanics of how red light therapy impacts your health.

Light Penetration 101

What we call “light” is electromagnetic radiation that is visible to the human eye. Our bodies also perceive other types of electromagnetic radiation, including radio, infrared, and ultraviolet (UV). But we don’t see electromagnetic radiation outside the limited spectrum of visible light; rather, we perceive this radiation with our other senses, such as feeling invisible infrared wavelengths as heat.

When electromagnetic waves disperse from their source, they interact with whatever is around them. They will either reflect off objects (this is what makes objects visible), pass through them, or absorb into them.

If you are in the middle of a supermarket, your cell phone can still receive signals from a cell tower since radio waves can pass through many types of solid wall materials. You can see the walls but not through them, whereas a camera with a heat (infrared) sensor could point out humans outside the walls.

Light has similar effects on the body's cells, whether it comes from the sun, overhead lights, or a computer screen. Very short wavelengths will barely absorb into the outermost layers of the skin. The longer the wavelength, the deeper it will penetrate into the body.

When light leaves its source, whether that source is the sun or an LED bulb, it begins to spread out or scatter. However, the rate at which it scatters depends on its wavelength. Blue light has very short wavelengths which scatter easily; the longer red and near-infrared light wavelengths scatter at a much slower rate, which means they remain more intense for a longer period. 

Longer wavelengths may pass all the way through if the body part is shallow enough, such as the ears or hands; but on that same body part, most blue light is deflected.

Light shining through hands
One important thing to know is that when we see sunlight, it appears to be white, but it’s actually all the colors in the spectrum: red, orange, yellow, green, blue, indigo, and violet. Each of these colors is a different sized wavelength.

A simple experiment with a flashlight illustrates how some wavelengths of light can penetrate the body while others can’t. Hold the flashlight up to your hand. The other side of your hand will glow red because only red wavelengths are long enough to pass completely through your hand. Shorter wavelengths will absorb or bounce off the skin but won’t penetrate all the way through.

If you hold a red light device up to your palm, the effect on the back of your hand will be even more dramatic because all of the light passing through your hand is red. But if you hold a blue light device next to your hand, none of the light would pass through, and the backside of your hand will look normal.

So what happened to the violet, blue, green, and yellow wavelengths? They are too short to pass through your hand. While these wavelengths have biological effects on the human body, their effects are limited due to shallow absorption. 

Light Wavelengths and Corresponding Penetration

During clinical trials, red and NIR wavelengths have shown great promise in treating a vast number of conditions. This is because they absorb deeper into the body than other wavelengths, and they do not cause damage to the tissues (like UV light does).

The average thickness of the epidermis (the outermost layer of skin) is 0.1mm, or about the thickness of a single sheet of paper. Beneath the epidermis lies the dermis and a protective subcutaneous fat layer that extends down to about 1.2mm. That may not seem like much for the light to pass through, but it's enough to block out most wavelengths.

An English study focused on the penetration depth of visible and invisible light.  In ideal situations, the therapeutic wavelengths and their penetration depths are:

diagram of light spectrum

  • UV wavelengths (380 to 450 nanometers, or nm) only penetrate the epidermis to 0.1mm. Due to its skin-damaging properties, UV therapy must be administered with extreme caution and only by a medical professional.
  • Blue wavelengths (450nm to 500nm) penetrate the dermo-epidermal junction at 1mm. Blue wavelengths can be damaging to skin, as well as potentially contribute to macular degeneration, so only doctors use it therapeutically to treat acne and precancerous lesions.
  • Green wavelengths (500nm to 570nm) penetrate to 2mm. Aside from migraine pain, there is little evidence to suggest green wavelengths have many beneficial effects on the body.
  • Yellow/Amber wavelengths (570nm to 620nm) penetrate to 3mm. Very few studies have been done on these wavelengths, but they may play a role in boosting moods.
  • Red wavelengths (620nm to 750nm) penetrate to 4mm. They are best known for stimulating collagen production, thereby making red light therapy a powerful anti-aging tool.
  • Near-infrared wavelengths range from 750nm to 2,500nm. The most therapeutic NIR wavelengths range from 750nm to 850nm and penetrate to 5mm. 

Penetration depths are influenced by physical blockers (the body’s natural sunscreen) and the effect of scattering (dispersion) as light photons move through the body's fluids and tissues.

Physical Blockers and Natural Sunscreen

The body’s natural response to protect itself from UV damage is to increase pigmentation by boosting melanin production—what we know as tanning. More melanin in the skin means more photoprotection. While tanning can protect the skin, it is actually a sign that damage has been done.  

Red/NIR wavelengths do not stimulate melanin production, which means that the body won’t produce light-blocking melanin as a response to red or NIR wavelengths.

For deep penetrating light therapy, red and NIR light should be administered to bare skin (clothing will block light) that is free of sunscreen. There is no evidence that red/NIR wavelengths can cause skin damage that could block incoming light photons. 

Red Light/NIR Light Together Are a Powerful Combination

Since deep penetrating red and NR light therapy is more beneficial than green or blue light, it may seem that deeper would be better. But the truth is, you want to stimulate both the surface and the inner workings of the body.

The well-being of the skin goes hand-in-hand with the well-being of the underlying tissue. Combining multiple red/NIR wavelengths delivers the maximum benefits simultaneously.

Red Light vs Near-Infrared Light benefits

Red light therapy is most often used for stimulating the health of the skin—the largest organ in the body. PBM has been used successfully to improve skin tone, reduce signs of aging, minimize the appearance of fine lines and wrinkles, and boost collagen production. But there’s much more to skin health than youthful looks.

The skin is also an important part of the immune system. In a 2013 study co-authored by Dr. Michael Hamblin (one of the most widely respected authorities on red light), red light therapy boosts the immune system through reducing chronic inflammation, boosting microcirculation, activating stem cells, and stimulating the lymphatic system to remove toxins. 

The lymph nodes, for example, are located just below the skin surface. Stimulating their ability to remove toxins from the body can positively influence the health of individual cells, and supporting individual cell health will have a positive effect on surrounding cells and systems.

The limitation of red light wavelengths is that they can’t penetrate bone or absorb deep into muscles—but they have powerful effects on skin health. For issues such as deep muscle injury or brain health, turn to near-infrared wavelengths. NIR light sparks a systemic, or metabolic effect on the entire body, as well as localized effects. Stimulating cells at a deeper level could address underlying conditions such as systemic inflammation that slows healing.

In human clinical trials, deep penetrating NIR light has been used to treat joint aches, muscle spasms, traumatic brain injury, stroke, and anxiety and depression. NIR accelerates wound healing, improves bone repair and growth, and improves athletic performance. These all-body stimulating and anti-inflammatory effects can stimulate a chain reaction of improved health including pain relief and easing of chronic symptoms.

A multi-faceted red/NIR approach to light therapy has been clinically proven to yield the best results.

For example, a 2017 study suggests that resolving neuropathy pain can be achieved by both red and NIR light therapy. This combination is most effective because red light targets nerve endings just below the skin, while deep penetrating NIR light can address inflammation in the brain that may be causing nervous system dysfunction. 

Using multiple wavelengths within the “therapeutic window” of red (630nm to 660nm) and NIR (810nm to 850nm) simultaneously is possible with the PlatinumLED BIOMAX series, which uses a proprietary array of five different red and NIR wavelengths in proportions that have the most profound effects on the body when used together.

How to Achieve Deep Light Penetration

In today’s market, choosing the right deep penetrating red light therapy device can be overwhelming. You’d be wise to cross many off your list of potentials, though. Many devices on the market do not deliver the spectrum of light that has been clinically proven to achieve the best outcomes, nor do they have the power needed to deliver the maximum light energy output to your body. 

You may have seen advertisements for a device such as a deep penetrating light (DPL) flex pad. Be aware that these devices rarely have the capacity to deliver light photons with enough power to penetrate beyond the outer layers of the skin.

Cross all battery-operated handheld devices off your list, even if they claim to deliver deep-penetrating light. Most emit low light energy output while consuming a lot of power. You won’t get the intensity of light required to achieve therapeutic benefits even when batteries are fresh, and performance will decline as batteries become depleted.  

Experience deep penetrating light therapy using: 

  1. A combination of red and/or NIR wavelengths;
  2. A device with the power to deliver the maximum number of light photons into the skin, so that as many as possible reach the targeted area rather than being dispersed in the outer layers of the skin.

High-quality LED panels will deliver the light energy needed for optimal therapeutic effects. When comparing devices, look for:

  • The ability to choose between red and NIR wavelengths (ideally, a combination);
  • The size of the panel, depending on your needs. Larger panels deliver more photoenergy, but over a wider area. You may not need a large panel if you just plan on using PBM to ease arthritis pain in your hands; but if you’re an athlete who wants to accelerate deep-muscle recovery from intense workouts, you’ll want a larger panel;
  • Light energy output: This does not mean power consumption, but output, or high irradiance, which refers to the number of light photons available to absorb into the skin and interact with the mitochondria. 

PlatinumLED Therapy Lights ensure clinical-grade PBM treatment that is impossible to achieve with low-output devices. Since 2010, PlatinumLED has been the global industry leader in LED therapy panels, offering the highest amount of irradiance for more power with deeper penetration, along with a patent-pending red/NIR spectral output (a beneficial blend of five different wavelengths that offer therapeutic benefits for many applications. The BIOMAX series panels can be linked together to fully customize your experience and optimize your results.

Using Your Panel to Achieve Maximum Red/NIR Penetration

person close to red light therapy devide

The closer you are to a device, the more intense the penetrating effects because the light doesn’t have a chance to scatter as much as if you were further from the device. A reputable company will specify the physical distance at which irradiance is measured. For more on this, check out our PlatinumLED comparison video.

When you are farther away from a panel, you won’t get the deep benefits, but you will get surface benefits. If you’re using a small panel for pain relief on finger arthritis, for example, the light that is dispersed over a larger area (up to your elbow) will still absorb into the skin. So, you could still experience an improvement in sun damage to your forearm skin, but not deep muscle recovery. To achieve deeper penetration, simply move closer to the panel.

Deep Penetration Means Profound Effects

Red light therapy can be seen as a therapeutic approach and not a cure. However, in recent years, PBM has become popular as adjunctive therapy for a variety of aesthetic and medical conditions ranging from improving the appearance of photoaged skin to pain relief, accelerated wound healing, and slowing down progressive cognitive decline from neurodegenerative disorders such as Alzheimer’s and Parkinson’s. 

PBM has shown immense potential in so many different areas that its clinically studied benefits are too vast to list here. Check out the PlatinumLED blog for more on how you can use this safe and natural non-invasive therapy to enhance your well-being.