Part 6 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
🎧 ▶️ Press the play button below to listen.
Introduction
You have followed the series so far.
You know that near-infrared (NIR) light penetrates skin, fat, muscle, and bone. You know it reaches your brain. You know it triggers mitochondrial melatonin — a powerful antioxidant produced inside your cells, not the pineal gland.
You know that sunlight is free NIR. Hair and hats can block it. That you can optimize your exposure.
But now comes the central question of this entire series:
How does NIR light actually protect your brain?
What happens from the moment NIR photons touch your scalp to the moment your neurons fire more efficiently, your mood lifts, and your thinking sharpens?
This article is Part 6 of the Light on Healing series. We will trace the journey of NIR light — from scalp to synapse — and explore the multiple layers of neuroprotection that follow.
We will focus on general neuroprotection here: cognitive health, mood, anxiety, brain fog, and resilience against everyday stressors. The next article will dive into neurodegenerative diseases (Alzheimer’s, Parkinson’s) and traumatic brain injury.
Let us follow the light.
The Journey of a Photon: From Scalp to Neuron
Imagine a single NIR photon. It leaves a red light panel or the sun. It travels through the air and lands on your scalp.
What happens next?
Step 1: Scalp and Skin
The photon first encounters your scalp skin. NIR light at 810–850 nm passes through the epidermis and dermis with minimal resistance. Unlike UV, NIR does not damage DNA. Unlike visible light, NIR is not scattered heavily by skin pigments.
If you have hair, some photons are absorbed by melanin or scattered by hair shafts. But many pass through — especially if you part your hair or have thin, light-colored hair.
Step 2: Skull Bone
This is where NIR shines.
Your skull is about 5–7 mm thick. Visible light cannot penetrate bone. But NIR — specifically wavelengths between 700 and 1200 nm — passes through bone surprisingly well. Bone is mostly calcium phosphate and collagen, both of which are relatively transparent to NIR compared to soft tissue.
Step 3: Meninges and Cerebrospinal Fluid (CSF)
Below the skull are three protective layers (meninges) and a cushion of cerebrospinal fluid. NIR passes through these without significant absorption. The CSF is mostly water, and water absorbs NIR minimally at these wavelengths.
Step 4: Brain Tissue and Neurons
Finally, the photon reaches its destination: brain tissue.
Here, it is absorbed by cytochrome c oxidase inside the mitochondria of neurons, astrocytes, and other brain cells. This absorption triggers the cascade of benefits we have discussed — increased ATP, reduced nitric oxide blockage, and the production of mitochondrial melatonin.
But that is only the beginning.
From this single absorption event, a chain reaction of neuroprotection unfolds. Let us explore each layer.
Layer 1: Cellular Energy (ATP)
The most immediate effect of NIR light on your brain is more energy.
Neurons are energy-hungry cells. They consume about 20% of your body’s oxygen and glucose despite making up only 2% of your body weight. When neurons do not have enough ATP, they function poorly.
Think of ATP as the fuel for every thought, memory, and emotion.
- Low ATP → brain fog, slow thinking, poor memory, low mood
- High ATP → sharp thinking, quick recall, mental clarity, resilience
NIR light boosts ATP production by activating cytochrome c oxidase. More electrons flow through the electron transport chain. More ATP is generated.
This is not a drug that forces neurons to work harder. It is a natural enhancement of your cells’ own energy systems. And because NIR reaches deep brain regions (prefrontal cortex, hippocampus, and even the cerebellum), the energy boost is widespread.
Clinical evidence: Multiple human studies have shown that a single session of transcranial PBM improves cognitive performance in healthy adults within minutes. Faster reaction times. Better working memory. Improved attention.
That is ATP at work.
Layer 2: Mitochondrial Melatonin (Antioxidant Protection)
As you learned in Part 1 of this series, NIR light triggers the production of mitochondrial melatonin — a local antioxidant produced inside your mitochondria.
This is distinct from the melatonin you take as a sleep supplement.
- Sleep melatonin (pineal gland) → helps you fall asleep
- Mitochondrial melatonin (brain cells) → neutralizes free radicals
Why does your brain need this?
Because your brain is extraordinarily vulnerable to oxidative stress.
| Vulnerability | Why It Matters |
|---|---|
| High oxygen consumption | Your brain uses 20% of your body’s oxygen, producing many free radicals |
| High fat content | Neuron membranes are rich in polyunsaturated fats, which oxidize easily |
| Low natural antioxidants | The brain has fewer antioxidant defenses than the liver or kidneys |
Mitochondrial melatonin solves this problem. It is produced exactly where free radicals are generated — inside the mitochondria — and neutralizes them immediately.
Without enough mitochondrial melatonin, free radicals accumulate. They damage mitochondrial DNA, break down cell membranes, and trigger inflammation. Over time, this damage accelerates brain aging.
NIR light gives your brain a continuous supply of this protective melatonin — not from a pill, but from your own cells.
Layer 3: Reduced Neuroinflammation
Inflammation is your immune system’s response to injury or infection. In the brain, it is called neuroinflammation.
Acute neuroinflammation (from infection or injury) is protective. But chronic, low-grade neuroinflammation is destructive. It is now recognized as a driver of:
- Depression and anxiety
- Brain fog and fatigue
- Cognitive decline
- Neurodegenerative diseases
NIR light reduces neuroinflammation through several mechanisms:
1. Lowering pro-inflammatory cytokines
Cytokines are signaling molecules that promote inflammation. NIR light has been shown to reduce levels of TNF-alpha, IL-1 beta, and IL-6 — all of which are elevated in chronic neuroinflammation.
2. Activating anti-inflammatory pathways
NIR light increases levels of IL-10 and other anti-inflammatory signals. This shifts the brain’s immune environment from destructive to healing.
3. Modulating microglia
Microglia are the brain’s resident immune cells. When overactivated, they can damage healthy neurons. NIR light calms overactive microglia, reducing collateral damage.
Clinical evidence: Human studies have shown that transcranial PBM reduces symptoms of depression and anxiety, conditions closely linked to neuroinflammation. Patients report better mood, less rumination, and improved emotional regulation.
Layer 4: Increased Blood Flow and Oxygenation with NIR
Your brain needs blood. Blood delivers oxygen and glucose while removing waste products.
Poor blood flow to the brain (hypoperfusion) is linked to:
- Brain fog
- Fatigue
- Depression
- Cognitive decline
- Vascular dementia
NIR light increases cerebral blood flow through two mechanisms:
1. Nitric oxide (NO) release
As discussed in Part 3, NIR light knocks nitric oxide off cytochrome c oxidase. This free nitric oxide then diffuses to blood vessels, where it causes vasodilation — widening of blood vessels. Wider vessels mean more blood flow.
2. Increased angiogenesis
Over time, repeated NIR exposure stimulates the growth of new capillaries (angiogenesis). This improves long-term blood supply to brain regions.
Clinical evidence: Functional near-infrared spectroscopy (fNIRS) studies show that transcranial PBM increases oxygenated hemoglobin in the prefrontal cortex within minutes of treatment. This is a direct, measurable increase in brain blood flow.
Layer 5: Neuroplasticity and Brain Repair
Neuroplasticity is your brain’s ability to rewire itself — to form new connections, strengthen existing ones, and prune away unused ones.
It is the biological basis of learning, memory, and recovery from injury.
NIR light enhances neuroplasticity through several pathways:
1. Brain-derived neurotrophic factor (BDNF)
BDNF is often called “fertilizer for the brain.” It supports the survival of existing neurons and encourages the growth of new synapses. NIR light has been shown to increase BDNF levels in animal models and human studies.
2. Synaptic strengthening
More ATP means more energy for synaptic transmission. Stronger synapses mean faster, more reliable communication between neurons.
3. Neurogenesis (new neurons)
While most adult neurogenesis occurs in the hippocampus, NIR light may support the survival of newly formed neurons. This is particularly relevant for memory and mood.
Clinical evidence: Studies in healthy adults have shown that transcranial PBM improves performance on learning tasks. Participants learn faster, remember better, and show greater improvements over multiple sessions.
Layer 6: Mood and Emotional Regulation
Depression and anxiety are not just “chemical imbalances.” They are complex conditions involving energy metabolism, inflammation, blood flow, and neuroplasticity — all of which NIR light addresses.
Several randomized controlled trials have examined transcranial PBM for depression.
Key findings:
- A single NIR treatment to the forehead reduced depression and anxiety scores within two weeks
- Multiple treatments produced sustained improvements
- Effects were comparable to antidepressant medications in some studies, but without the side effects (weight gain, sexual dysfunction, withdrawal)
Why does NIR light help mood?
- Increased ATP → more energy for emotional regulation
- Reduced neuroinflammation → less inflammatory signaling that contributes to depression
- Increased blood flow to the prefrontal cortex → better executive function and emotional control
- Enhanced neuroplasticity → ability to “unlearn” negative thought patterns
NIR light is not a cure for clinical depression. But it is a promising, low-risk intervention for mild-to-moderate symptoms — and a supportive tool for those undergoing other treatments.
Layer 7: Brain Fog, Fatigue, and Cognitive Clarity
Brain fog is not a medical diagnosis. But it is a real experience — feeling mentally sluggish, forgetful, unable to focus, easily distracted.
It can result from:
- Poor sleep
- Chronic stress
- Inflammation
- Low ATP
- Poor blood flow
NIR light addresses all of these.
Clinical evidence: Studies in healthy adults show that transcranial PBM improves:
- Reaction time
- Working memory
- Attention and focus
- Processing speed
These effects are seen within minutes of a single session and accumulate with repeated treatments.
For people with chronic fatigue syndrome, fibromyalgia, or post-COVID cognitive impairment (“brain fog”), NIR light offers a non-pharmaceutical way to support brain function.
Putting It All Together: The Neuroprotection Cascade
Here is how the layers work together in sequence:
| Step | What Happens | Timeframe |
|---|---|---|
| 1 | NIR light reaches brain cells | Instant |
| 2 | Cytochrome c oxidase absorbs light | Milliseconds |
| 3 | ATP production increases | Seconds to minutes |
| 4 | Mitochondrial melatonin is produced | Minutes |
| 5 | Free radicals are neutralized | Minutes to hours |
| 6 | Nitric oxide is released, increasing blood flow | Minutes |
| 7 | Inflammation decreases | Hours to days |
| 8 | BDNF increases | Hours to days |
| 9 | Neuroplasticity improves | Days to weeks |
| 10 | Mood, cognition, and resilience improve | Days to weeks |
This is not magic. It is biology. And it explains why a single NIR session can produce immediate benefits (more energy, better focus) while repeated sessions produce lasting changes (better mood, sharper thinking, reduced brain fog).
Practical Takeaways for Your Own Brain
You do not need to wait for a diagnosis to start supporting your brain.
Here is how to apply what you have learned:
Use natural NIR (sunlight) daily. Morning and late-afternoon sun on your skin (especially the scalp, face, and neck) triggers mitochondrial melatonin without UV risk.
Consider an NIR device if you cannot get regular sun exposure or want targeted brain therapy. Look for 810–850 nm, adequate irradiance, and proper dosing.
Be consistent. The benefits of NIR light accumulate over time. A single session helps. Regular sessions transform.
Combine with other brain-healthy habits. NIR light is not a substitute for sleep, exercise, good nutrition, stress management, and social connection. It is a complement.
Start now. Brain health is not something to think about in your 60s. The earlier you start supporting your mitochondria, the longer your brain will serve you well.
Conclusion
The journey from scalp to synapse is short in distance — millimeters — but vast in biological consequence.
NIR light penetrates skin, bone, and brain tissue. It is absorbed by cytochrome c oxidase in your neurons’ mitochondria. This single event triggers a cascade of neuroprotection:
- More ATP (energy)
- Mitochondrial melatonin (antioxidant)
- Reduced neuroinflammation
- Increased blood flow
- Enhanced neuroplasticity
- Better mood and cognition
These mechanisms work together to protect your brain from everyday stress, inflammation, and oxidative damage. They improve how you think, feel, and function — not just in old age, but right now.
The next article will explore how these same mechanisms apply to Alzheimer’s, Parkinson’s, and traumatic brain injury.
But do not wait for a diagnosis. Your brain is protecting you every moment of every day. It deserves the same in return.
Let the light in.
Takeaway Messages
- NIR light penetrates scalp, skull, and brain tissue — reaching neurons directly.
- Inside neurons, NIR is absorbed by cytochrome c oxidase in mitochondria.
- This increases ATP production — more energy for thinking, memory, and mood.
- NIR triggers mitochondrial melatonin — a local antioxidant that neutralizes free radicals.
- NIR reduces neuroinflammation by lowering pro-inflammatory cytokines and calming microglia.
- NIR increases cerebral blood flow via nitric oxide release and the formation of new capillaries.
- NIR enhances neuroplasticity by raising BDNF and strengthening synapses.
- Human studies show NIR improves cognitive performance, mood, anxiety, and brain fog.
- Benefits appear within minutes (ATP, blood flow) and accumulate over weeks (neuroplasticity, mood).
- NIR is not a substitute for sleep, exercise, or good nutrition — but it is a powerful complement.
- Start now. Brain health is a lifelong investment, not a last-minute repair.
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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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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