Functional Medicine

Red Light Therapy for the Brain: Cognitive Performance, TBI, and Recovery

By Dr. Cameron Chesnut | Five Codes Podcast

This is the application of red light therapy that most people have never heard of, and it may be the most consequential one. Near infrared light at the right wavelengths can penetrate through bone, including the human skull, and produce measurable improvements in brain function. The applications range from traumatic brain injury recovery to cognitive performance to post-surgical brain fog.

I have been sitting in front of a red light panel before surgery every single day of my career. Knowing now what that was doing to my brain during those sessions, not just my skin and physiology, makes those years of intuitive habit feel well-earned.

This post is part of our complete red light therapy series.

How Near Infrared Light Reaches the Brain

Near infrared light in the 810 to 860 nm range has a long enough wavelength and low enough energy that it can pass through biological tissue with significant depth. This includes bone. The human calvarium (skull) is not an impenetrable barrier to near infrared light. Multiple studies have demonstrated measurable penetration of 810 to 860 nm light through the skull to superficial cortical tissue.

This is the basis for a clinical approach called transcranial photobiomodulation (tPBM): the application of near infrared light to the head, transcranially, to deliver photobiomodulatory effects directly to neural tissue.

The brain, like the retina, has extremely high mitochondrial density. It is one of the most energetically demanding tissues in the body, consuming roughly 20% of total body energy despite comprising only about 2% of body mass. This makes it highly responsive to interventions that improve mitochondrial efficiency. Red light hits cytochrome C oxidase in neural mitochondria, releases bound nitric oxide, increases ATP production, reduces oxidative stress, and improves local blood flow through vasodilation.

For a deeper read: Naeser MA et al. Significant improvements in cognitive performance post-transcranial, red/near-infrared light-emitting diode treatments in chronic, mild traumatic brain injury. Journal of Neurotrauma, 2014. (PubMed)

Clinical Applications: What the Evidence Supports

Traumatic Brain Injury and Concussion

When the brain experiences trauma, its metabolic demand spikes dramatically as it attempts repair, while neuroinflammation simultaneously impairs the mitochondrial function needed to meet that demand. This energy-inflammation mismatch is a central driver of post-concussive symptoms: brain fog, difficulty concentrating, word-finding problems, mood changes, and fatigue.

Transcranial near infrared therapy addresses this directly. Clinical trials have demonstrated meaningful improvements in cognitive function, memory, attention, and symptom burden in patients with mild to moderate TBI receiving transcranial photobiomodulation. The mechanism is well-matched to the pathology: more ATP, less neuroinflammation, better cerebral blood flow.

For a deeper read: Henderson TA and Morries LD. Near-infrared photonic energy penetration: can infrared phototherapy effectively reach the human brain? Neuropsychiatric Disease and Treatment, 2015. (PubMed)

Stroke Recovery

Post-stroke, the metabolic burden of neural repair is extreme. Surviving tissue around the infarct zone must work to compensate for lost function, and inflammation in the damaged area creates significant ongoing metabolic stress. Transcranial near infrared therapy has been evaluated in stroke recovery and has demonstrated benefit in accelerating functional recovery in both animal models and human trials. This is an exploratory but promising area, not yet a standard of care.

Neonatal Hypoxic Brain Injury

This is perhaps the most striking illustration of both the efficacy and safety of transcranial near infrared therapy. In London and several other centers, near infrared light is being applied to the heads of newborn infants immediately following hypoxic (low oxygen) brain injuries at birth. These infants are demonstrating improved neurological outcomes compared to controls.

That this intervention could be considered appropriate and safe for application to hours-old newborns is the clearest possible signal that the safety profile of near infrared light on neural tissue is excellent. If it did not work, it would not be used on neonates. If it were dangerous, it would never have been approved for neonates. Both the efficacy and the safety case are made simultaneously by this application.

Note: some investigational work is occurring (especially with near‑infrared spectroscopy systems), but routine clinical use on newborns is not yet widespread or part of official neonatal resuscitation standards.

Mood, Anxiety, and Depression

Red and near infrared light applied to the prefrontal cortex has shown benefit for depressive symptoms and anxiety in clinical studies. The mechanism likely involves improved mitochondrial function in cortical neurons and increased cerebral blood flow to prefrontal regions, which are known to show reduced activity in depression.

This is consistent with a pattern seen throughout photobiomodulation research: benefits appear most strongly in tissues under metabolic stress, and the prefrontal cortex in depression is a tissue under precisely that kind of stress.

For a deeper read: Schiffer F et al. Psychological benefits 2 and 4 weeks after a single treatment with near infrared light to the forehead. Behavioral and Brain Functions, 2009. (PubMed)

Eye Health: The Most Mitochondria-Dense Tissue in the Body

The retina contains the highest density of mitochondria of any tissue in the human body. This makes it extraordinarily responsive to photobiomodulation.

Age-related macular degeneration (AMD). Dry AMD results from progressive mitochondrial senescence in retinal cells. It is one of the leading causes of blindness worldwide, and there are limited conventional treatment options. Red light therapy for dry AMD has received regulatory approval in several countries and has demonstrated meaningful benefit in slowing progression. In January 2025, the FDA authorized a light therapy device for dry AMD.

Color vision and visual acuity. Even in healthy eyes, a brief red light exposure (studies have used low-energy red flashlights for just a few minutes) improves color differentiation for up to five days afterward. The ability to distinguish difficult-to-discriminate colors, particularly dark colors close in the spectrum, measurably improves after red light exposure to the retina.

For a deeper read: Shinhmar H et al. Optically improved mitochondrial function redeems aged human visual decline. Journals of Gerontology, 2020. (PubMed)

Red Light and Post-Operative Cognitive Dysfunction

This application is personal to my practice and represents one of the areas where I am applying mechanism to clinical context ahead of formal trial data.

Post-operative cognitive dysfunction (POCD) is a well-recognized phenomenon in which patients experience cognitive impairment, word-finding difficulties, and brain fog following surgery, particularly surgery involving general anesthesia. The underlying driver is neuroinflammation combined with the metabolic stress of anesthesia on neural tissue.

I am already focused on minimizing the causes of POCD in my surgical practice: selecting anesthetic approaches that minimize neuroinflammatory burden, optimizing patient metabolic health before surgery, and supporting recovery aggressively afterward.

Near infrared light applied transcranially after surgery is mechanistically exactly what this situation calls for: more ATP for inflamed, metabolically stressed neural tissue, nitric oxide released in cerebral vasculature, reduced oxidative burden in cortical neurons. There are not yet formal clinical trials specifically evaluating tPBM for POCD. But the mechanism is coherent, the safety profile is excellent, and the existing evidence from TBI and other neuroinflammatory contexts is supportive.

For patients recovering from procedures at Clinic 5C, our next level recovery protocol includes near infrared therapy as part of the post-surgical optimization approach.

My Pre-Surgical Protocol

Every day before I operate, I sit in front of a red light panel. This has been part of my pre-surgical flow state routine for my entire career.

At the time I started, I understood the skin and metabolic benefits. What I know now is that I was also: releasing nitric oxide in my cerebral vasculature, improving cytochrome C oxidase function in my cortical neurons, and potentially improving color discrimination and fine visual processing in my retina during the hours immediately following the session.

For a surgeon, fine color discrimination under operating room lights is not a trivial detail. Neither is cognitive clarity under high-stakes demands. The fact that red light applied to the face and head, in the context of a morning sauna session, was also priming my brain for peak performance is a gratifying confirmation of something I was doing before I had the full mechanistic picture.

Frequently Asked Questions

Can red light therapy penetrate through the skull?

Yes. Near infrared light at 810 to 860 nm has been demonstrated in multiple studies to penetrate through the human calvarium (skull bone) to reach superficial cortical tissue. This forms the scientific basis for transcranial photobiomodulation (tPBM), a clinical approach with growing evidence in TBI recovery, stroke, mood disorders, and cognitive performance. The penetration depth is not unlimited, but is sufficient to reach the outer layers of cortical tissue from external scalp application.

Does red light therapy improve memory and focus?

The existing evidence is positive but still developing. Studies in TBI patients demonstrate meaningful improvements in memory, attention, and executive function following transcranial photobiomodulation. In healthy individuals, the evidence for cognitive performance enhancement is more limited but mechanistically plausible. The brain, as the most metabolically demanding tissue in the body, should in principle benefit from interventions that improve mitochondrial ATP production and reduce neuroinflammation. Studies specifically measuring cognitive performance in healthy subjects following tPBM show promising results.

Is red light therapy used in hospitals?

Yes, for specific applications. Transcranial near infrared therapy for neonatal hypoxic brain injury is in clinical use in several major medical centers including in London. Red light therapy for dry AMD has received FDA authorization. Photobiomodulation for oral mucositis in oncology patients is used in cancer centers and is recognized by clinical oncology guidelines. The hospital-based applications tend to be more targeted and higher-powered than consumer devices, but the underlying technology is the same.

Can red light therapy help with brain fog after surgery?

Mechanistically, yes. Post-operative cognitive dysfunction (POCD) and post-surgical brain fog are driven by neuroinflammation and the metabolic stress of anesthesia on neural tissue. Transcranial near infrared therapy reduces neuroinflammation and improves mitochondrial ATP production in stressed neural tissue, which is precisely the deficit driving these symptoms. Formal clinical trials specifically in POCD have not yet been published, but the mechanism is coherent and the evidence from analogous neuroinflammatory conditions (TBI, stroke) is supportive.

Is red light safe to use near the eyes?

Red and near infrared light at therapeutic doses is not ionizing and does not damage the DNA or photoreceptors of the eye the way ultraviolet light does. The retina is actually one of the most responsive and apparently benefited tissues from red light exposure, given its extreme mitochondrial density. Closing your eyes in front of a red light source still allows red and near infrared wavelengths to reach the retina, as these wavelengths penetrate through the eyelid. Direct, close staring at a very high-powered LED source is not recommended, but standard therapeutic doses from recommended distances present minimal retinal risk and potential benefit.

What is transcranial photobiomodulation (tPBM)?

Transcranial photobiomodulation is the application of near infrared light to the scalp and head with the intention of delivering photobiomodulatory effects to underlying neural tissue. Because near infrared light at 810 to 860 nm penetrates through the skull, this approach can influence brain tissue non-invasively from external application. Clinical research has evaluated tPBM for traumatic brain injury, stroke recovery, depression, anxiety, cognitive performance, and neurodegenerative conditions. It is a developing but evidence-supported application of photobiomodulation.

Continue reading our full red light series:

Dr. Cameron Chesnut is a facial plastic surgeon and founder of Clinic 5C. Views expressed are his own and are not affiliated with the University of Washington School of Medicine. This content is for educational purposes only and is not individual medical advice.

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