Part 9 of the series: Light on Healing: How Red Light and Sunlight Protect Your Aging Brain
- Part 1: Melatonin: Not Just a Sleep Hormone – The Mitochondrial Antioxidant You’ve Never Heard Of
- Part 2: The Surprising Secret of Blue Zones: Daily Sunlight Heals
- Part 3: What Is Photobiomodulation? Red Light, NIR, and the Skin-Brain Axis
- Part 4: Does Hair Block Near-Infrared Light? A Practical Guide
- Part 5: Does a Hat or Clothing Block Near-Infrared Light?
- Part 6: From Scalp to Synapse: NIR, Melatonin, and Brain Protection
- Part 7: Can Near-Infrared Light Slow Cognitive Decline?
- Part 8: Practical Near-Infrared Protocols for Brain Health
🎧 ▶️ Press the play button below to listen.
Introduction
You have followed the series.
You know that near-infrared (NIR) light penetrates skin, muscle, and bone. You know it triggers mitochondrial melatonin, increases ATP, reduces inflammation, and protects the brain.
You know how to use sunlight. You know what to look for in a device. You know how to track progress at home.
But if you have dark skin — Brown, Black, or deeply tanned — you may have asked yourself an honest question:
Does my skin color block NIR light? Will I get less benefit?
This is not a political question. It is a scientific one. And it deserves a straight answer.
This article provides that answer.
We will cover:
- What melanin is and how it interacts with NIR light
- What the research actually shows about skin tone and NIR penetration
- Practical adjustments for darker skin (small and easy)
- What does NOT change — brain benefits, mitochondrial melatonin, and intelligence
- Inclusive protocols for all skin types
Let us begin with the science.
Who This Article Is For
This article is for anyone with naturally dark skin — including people of African, South Asian, Southeast Asian, Indigenous, Middle Eastern, and Latin American descent — as well as those with deeply tanned skin from sun exposure.
If your skin is Brown, Black, olive, or deeply pigmented, this article speaks directly to you.
If you have light skin, this article will help you understand why PBM works differently for different people — and why inclusive protocols matter.
What Is Melanin and Why Does It Matter?
Melanin is the natural pigment in your skin, hair, and eyes. Its primary job is to protect you from ultraviolet (UV) radiation.
When UV light hits your skin, melanin absorbs it and converts it into heat — preventing UV from damaging your DNA. This is why people with darker skin are less likely to get sunburned or develop skin cancer from UV exposure.
But NIR light is not UV light.
NIR has longer wavelengths (700–1200 nm) than UV (280–400 nm). It does not damage DNA. It does not cause sunburn. And while melanin does absorb some NIR, it does so far less efficiently than it absorbs UV.
Think of melanin as a filter — not a wall. It absorbs some light, but much passes through.
The Key Difference: Skin Is Not Clothing
You may remember from our previous article, Does a Hat or Clothing Block Near-Infrared Light?, that dark clothing blocks most NIR light. A black shirt absorbs and scatters light, preventing it from reaching your skin.
But skin is not clothing. Here is why:
| Feature | Dark Clothing | Dark Skin |
|---|---|---|
| Thickness | 0.5–2 mm of dense fabric | 0.05–0.1 mm of living tissue (the melanin layer is extremely thin) |
| Absorption vs. Blocking | Absorbs and scatters light away from the body | Absorbs some light but is very thin — most NIR passes through |
| Heat effect | Fabric heats up and stays hot | Skin warms slightly, but blood flow cools it continuously |
| Can you remove it? | Yes | No (but you do not need to) |
The bottom line: The melanin layer in skin is only about 0.05–0.1 mm thick — roughly the thickness of a sheet of paper. NIR light penetrates several centimeters into the body. A tiny fraction of that penetration depth is absorbed by melanin. The vast majority passes through to reach muscle, bone, and brain.
What the Research Actually Shows
Research on skin tone and NIR penetration is limited — most PBM studies have been conducted on light-skinned participants. But the available evidence is clear.
The 2025 NIH Simulation Study
A 2025 study using computer simulations measured how much NIR energy reaches the brain through different skin tones.
What they found:
- Lighter skin (Caucasian) allows the highest energy accumulation in the brain
- Darker skin (Black/African) allows slightly less — but still significant — energy accumulation
- The difference is modest and can be overcome with simple adjustments
The authors concluded: “Variations in dosage could be overridden by a difference in skin tone,” meaning that the same device settings will deliver a slightly lower dose to the brain in darker skin, but this can be corrected by adjusting the protocol.
What About Red Light (660 nm)?
Red light (600–700 nm) is absorbed more strongly by melanin than NIR (800–850 nm). For people with darker skin, red light may be significantly less effective at penetrating deep tissue.
Recommendation: Prioritize NIR wavelengths (810–850 nm or longer) over red light if you have darker skin.
What About Longer NIR (1064 nm)?
Emerging research suggests that longer NIR wavelengths (e.g., 1064 nm) penetrate more effectively through melanin than shorter NIR (810 nm). If you have darker skin and can access a device with 1064 nm, that may be optimal.
Does Darker Skin Mean Less Brain Benefit?
You have followed this series.
Part 5 (From Scalp to Synapse: NIR, Melatonin, and Brain Protection) explained how NIR light penetrates the skull, triggers mitochondrial melatonin, increases ATP, reduces inflammation, and enhances blood flow — all of which protect your brain.
Part 6 (Can Near-Infrared Light Slow Cognitive Decline?) reviewed the clinical evidence showing that transcranial PBM improves cognition in mild cognitive impairment, mobility in Parkinson’s disease, and may slow the progression of Alzheimer’s disease.
Part 8 (Practical Near-Infrared Protocols for Brain Health) gave you specific protocols for using sunlight and devices to achieve those benefits.
Now, after all of that, you arrive at the logical next question:
If I have darker skin — Brown, Black, or deeply tanned — will I get less of those brain benefits?
It is an honest question. And it deserves a straight answer.
No. Darker skin does not mean less brain benefit. Here is why.
| Factor | Explanation |
|---|---|
| Adjustable protocols | People with darker skin can use slightly longer wavelengths or slightly longer session times to achieve the same brain dose. |
| Systemic effects | NIR applied anywhere on the body (arms, legs, back, chest) triggers mitochondrial melatonin and reduces inflammation systemically. Even if scalp absorption were slightly higher, full-body NIR still benefits the brain. |
| No studies show less benefit | No clinical trial has ever shown that people with darker skin get less cognitive benefit from PBM. The mechanisms are identical across all skin tones. |
| The brain does not know skin color | Once NIR reaches brain tissue, the biological response is the same regardless of skin tone. Mitochondria do not have melanin. |
Does Skin Color Affect Intelligence?
Absolutely not. This question must be addressed directly because it touches on harmful historical pseudoscience.
Intelligence is determined by genetics, nutrition, education, environment, sleep, stress, social factors, and countless other variables — not by skin color or NIR absorption.
There is zero scientific evidence that skin tone affects intelligence. The idea that it might is a false inference from a misunderstanding of physics and biology.
To be clear:
- NIR light is not the sole determinant of brain health. It is one small, supportive tool among many.
- Even if NIR absorption differed slightly (which it does, but only slightly), that would not translate into differences in intelligence.
- No credible scientist has ever proposed a link between skin pigmentation and cognitive capacity.
Skin color does not determine your brain’s destiny.
Practical Adjustments for Darker Skin
If you have darker skin, you do not need to avoid PBM. You just need to make small adjustments.
| Adjustment | Why | How Much |
|---|---|---|
| Use longer NIR wavelengths | 850–1064 nm penetrates better through melanin than 810 nm | Prefer devices with 850 nm or add 1064 nm if available |
| Increase session time | Compensates for slightly higher surface absorption | Add 10–20% time (e.g., 20 min → 22–24 min) |
| Monitor skin temperature | Darker skin heats up faster | If skin feels hot, increase distance from device |
| Prioritize NIR over red light | Red light is absorbed more by melanin | Use 810–850 nm or longer for brain applications |
| Perform a patch test | Check for any adverse reaction | Test on small area of skin (e.g., inner arm) for 5 minutes. Wait 24 hours. |
Sample Protocol for Darker Skin (Brain Health)
| Parameter | Standard Protocol | Adjusted for Darker Skin |
|---|---|---|
| Wavelength | 810–850 nm NIR | 850 nm or 1064 nm preferred |
| Session length | 20 minutes | 22–24 minutes (add 10–20%) |
| Frequency | 5–6 days/week | Same |
| Distance from device | 6 inches | 6–8 inches (slightly farther if skin feels hot) |
| Red light (660 nm) | Optional for skin | Reduce or avoid; prioritize NIR |
What About Sunlight for Darker Skin?
Sunlight contains NIR. And the same principles apply.
| Question | Answer |
|---|---|
| Does darker skin absorb more NIR from sunlight? | Yes, slightly — at the very surface |
| Does that mean less NIR reaches the brain? | Very slightly, but sunlight is so intense that it still delivers plenty of NIR |
| Should people with darker skin avoid sunlight? | No — they should use sensible, non-burning exposure, same as everyone |
| Do the Blue Zone centenarians with darker skin (Nicoya, Okinawa) get benefits? | Yes — they have low oxidative stress and low dementia rates despite their skin tone |
The bottom line: Sunlight is free and powerful. Even with darker skin, morning and late afternoon sun deliver significant NIR to your body and brain. Do not avoid it.
A Note on the Research Gap
It is honest to acknowledge that most PBM research has been conducted on light-skinned participants. This is a gap in the literature.
| What We Need | Why |
|---|---|
| More clinical trials with diverse skin tones | To confirm that protocols work equally well for everyone |
| Better dosing guidance for Fitzpatrick skin types IV–VI | To provide evidence-based, not just theoretical, adjustments |
| Device manufacturers to test on diverse skin | To ensure products are marketed inclusively |
Until then, the best available science indicates that NIR penetrates all skin tones and that simple adjustments (longer wavelengths, slightly longer sessions) are likely sufficient.
What This Means for You
| If you have… | Your protocol should… |
|---|---|
| Light skin | Follow standard protocols from clinical trials |
| Medium / olive skin | Standard protocols likely work well; monitor skin temperature |
| Dark / Black / Brown skin | Use longer NIR wavelengths (850 nm+), add 10–20% more time, prioritize NIR over red light, monitor heat |
| Deeply tanned skin | Same as darker skin — the tan increases melanin temporarily |
Conclusion
Skin color does not determine your brain’s destiny.
NIR light penetrates all skin tones. The differences are small, adjustable, and have no bearing on intelligence or the fundamental benefits of photobiomodulation.
If you have darker skin, you may need slightly longer sessions or slightly longer wavelengths. That is all. You do not need to avoid PBM. You do not need to worry about your brain.
The light reaches you. Your mitochondria do not see color. And your brain — regardless of your skin tone — deserves the protection that NIR light can offer.
Takeaway Messages
- Melanin absorbs some NIR light — but the melanin layer is extremely thin (0.05–0.1 mm). Most NIR passes through.
- Dark skin is not like dark clothing. Clothing is thick and external. Skin is thin and living. They are not the same.
- Research shows that darker skin allows slightly less NIR to reach the brain — but the difference is modest and adjustable.
- Simple adjustments work: Use longer NIR wavelengths (850–1064 nm), add 10–20% more time, and monitor skin temperature.
- Prioritize NIR over red light if you have darker skin. Red light is absorbed more strongly by melanin.
- No study has ever shown that people with darker skin get less cognitive benefit from PBM.
- Skin color has absolutely no effect on intelligence. That idea has no scientific basis.
- Sunlight still works. Morning and late afternoon sun on bare skin delivers plenty of NIR, regardless of skin tone.
- The research gap is real. More clinical trials with diverse skin tones are needed.
- Do not avoid PBM because of your skin color. Use it with small adjustments. Your brain will thank you.
Don’t Get Sick!
About Dr. Jesse Santiano, MD
Dr. Santiano is a retired internist and emergency physician with extensive clinical experience in metabolic health, cardiovascular prevention, and lifestyle medicine. He reviews all medical content on this site to ensure accuracy, clarity, and safe application for readers. This article is for educational purposes and is not a substitute for personal medical care.
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References:
- Cassemiro, A., Motta, L. J., Fiadeiro, P., & Fonseca, E. (2024). Predictive model of the effects of skin phototype and body mass index on photobiomodulation therapy for orofacial disorders. Photonics, 11(11), 1038. https://doi.org/10.3390/photonics11111038
- Girasol, C. E., et al. (2026). Is photobiomodulation therapy free from racial bias? A narrative review of skin pigmentation. Sao Paulo Medical Journal, 144(2), e20253358. https://doi.org/10.1590/1516-3180.2025.03358
- Karsten, A. E. (2012). The effect of skin phototype on laser propagation through skin (Doctoral dissertation). University of Pretoria. https://core.ac.uk/search/?q=author%3A(Aletta%20Elizabeth%20Karsten)
- Sajida, H., & Kallepalli, A. (2025). Towards assessing patient eligibility for optical neural interfaces: a simulation approach. Paper presented at BioMedEng25, Glasgow, United Kingdom.
- Van Lankveld, H., Mai, A. Q., Lim, L., Hosseinkhah, N., Cassano, P., & Chen, J. J. (2025). Simulation-based dosimetry of transcranial and intranasal photobiomodulation of the human brain: the roles of wavelength, power density, and skin tone. Biomedical Optics Express, 16(8), 3295-3314. https://doi.org/10.1364/BOE.567345
Disclaimer:
This article is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician before making health decisions based on the TyG Index or other biomarkers.
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