Light Therapy for Brain Health

The science

Red light has become a popular wellness tool, but researchers are now investigating whether similar technology might have more targeted medical applications. Transcranial photobiomodulation (tPBM) is now an emerging treatment that uses low-level red or near-infrared (NIR) light to modulate brain function, with the goal of helping those with depression, mild cognitive impairment, and other brain conditions.  

It works by delivering specific wave lengths of light energy (typically 800–1064 nm) through the scalp, to stimulate energy-producing structures inside brain cells called mitochondria. When these wavelengths are absorbed, they appear to enhance cellular energy production and improve mitochondrial efficiency. This in turn may have several downstream benefits, including increased ATP production, enhanced blood flow in the brain, higher levels of a protein called brain-derived neurotrophic factor (BDNF), and reduced oxidative stress and inflammation. 

Together, these changes may help support brain cells’ resilience and synaptic plasticity, or the brain’s ability to form, strengthen, and reorganize connections. Because tPBM is most likely to deliver its strongest direct effects to superficial cortical regions, particularly the prefrontal cortex in current study designs, reported clinical improvements are most consistently observed in executive function, attention, and working memory—domains primarily mediated by the prefrontal cortex. That said, the degree of light penetration and the consistency of domain-specific clinical effects remain active areas of investigation.

The limited penetration to the hippocampus, which is deeper in the brain, likely explains why robust memory benefits are less frequently observed in clinical trials. All of this has prompted active research into tPBM as a potential tool for improving cognition, slowing neurodegenerative diseases like dementia, and treating mental health conditions.

The potential benefits

The following conditions have the most evidence behind them:

• Depression: Transcranial light therapy has shown promise for reducing depressive symptoms, with recent meta-analyses suggesting an overall moderate effect size across studies. Interestingly, some trials comparing whole-body red light therapy to transcranial light therapy show a stronger effect with whole-body therapy (although transcranial therapy may still be beneficial). The reasons for this difference are not yet established, but researchers have proposed this may be due to broader systemic effects on mitochondrial function, inflammation, and blood flow. 
• Cognitive impairment: tPBM has shown promising cognitive benefits in people with age-related cognitive impairment, including subjective cognitive complaints, mild cognitive impairment (MCI), and dementia, although the evidence is still limited and effects have not been shown to be similar across these groups. Studies and meta-analyses suggest improvements in global cognition, working memory, and some executive-function measures, with memory benefits reported in some but not all studies. Most of this evidence comes from transcranial rather than whole-body light therapy. Some studies show the benefits can persist for months, but durability remains an active area of study.
• Traumatic brain injuries (TBI): In TBI, tPBM has shown promising effects on cognitive efficiency, working memory, learning, sleep quality, pain, and post-concussion and PTSD symptoms in some studies, including a recent randomized placebo-controlled trial that found both statistically and clinically meaningful improvements. However, the evidence remains mixed, and not all randomized trials have shown benefits.
• Cognitive performance in healthy adults: Transcranial light therapy in healthy adults yields modest but significant improvements in working memory, attention, and some studies also report enhanced word finding. Effects on global cognition are less pronounced, and memory benefits are generally limited, likely due to the superficial penetration of light and the ceiling effect in high-functioning individuals.

These conditions have less evidence behind them, and more research is needed: 

• Anxiety: The effects on anxiety are mixed and less well studied than in depression, with some positive findings but insufficient evidence to draw firm conclusions.
• Stroke, Parkinson’s disease, and epilepsy: For these conditions, preclinical and early clinical studies suggest benefits in neuroprotection, neural repair, cerebral blood flow, and functional outcomes, but the evidence remains preliminary and large-scale trials are lacking.
• Other mental health conditions, including bipolar disorder: These have been studied only minimally. 

Usage guidelines

• The right wavelength: Most studies use 810–1064 nm, which is near infrared light, for optimal brain penetration. Visible red light (630–670 nm) is less commonly used for brain applications due to lower penetration.
• Power density: Published protocols use a broad range of densities,often between 20–250 mW/cm² at the scalp. Lower power densities (20–25 mW/cm²) have been common in some cognitive enhancement studies, while higher values up to 250 mW/cm² have also been used in cognitive, neurologic, and psychiatric protocols. Optimal dosing remains unsettled and likely depends on wavelength, pulse structure, treatment duration, target, and clinical indication
• The dose matters: For cognitive applications including mild cognitive impairment, dementia, and traumatic brain injury, research has typically used energy levels in the range of 1–10 J/cm², although protocols vary widely. Higher-dose approaches have also been studied, particularly in work examining blood flow to the brain, metabolism, and neuroprotection. However, higher doses do not necessarily produce stronger clinical benefits, and safety, individual tolerability, and anatomy need to be considered.
• Frequency is key: Protocols vary substantially, so you should always follow the instructions provided by a qualified health care professional or the specific device you’re using. In published tPBM studies, treatment frequency has ranged from about one to six sessions per week. For home LED panels or LED helmet devices (such as the Vielight), three sessions per week is common in many protocols, though some studies use more frequent schedules.
  • Laser-based devices can deliver higher power densities so often require less frequent sessions, such as one to three treatments per week. However, protocols vary widely for these too and depend on the dose, target, and indication rather than on the light source alone.
• Device type: Both lasers and LEDs appear capable of producing biologic and clinical effects. Some analyses suggest that device characteristics, including light source, may influence outcomes, but current data do not support a simple conclusion that one is consistently better than the other.
  • The most well studied devices direct infrared light at the head. Intranasal devices have also been studied, most often as an addition to transcranial treatment, but the data on this approach is still early and more data is needed.
• Individual factors: Hair can reduce light delivery because hair absorbs and scatters part of the incoming light before it reaches the scalp. This is one reason many studies target the forehead, where there is usually little or no hair, although helmet-style devices that treat hair-covered scalp have also shown positive results. Parting the hair may help, and in general, denser or thicker hair may reduce the amount of light that reaches the scalp and brain.
  • Similarly, skin pigmentation may also influence light penetration. Darker skin tones can increase absorption of some red and near-infraed wavelengths, which could reduce the dose reaching deeper tissues. However the magnitude of this effect in clinical practice is still being studied.
• The biphasic dose response: The biphasic dose response means that this often works best within an optimal dosing range: too little may have little effect, an intermediate dose may produce the greatest benefit, and too much may reduce that benefit (creating an upside down U shaped curve). Because this response can vary by wavelength, power, treatment duration, target, and condition, it’s important to work with a provider who can help you figure out the right dose for your specific condition.
• Safety: tPBM is generally well-tolerated, with minimal adverse effects reported. Physicians recommend that people always use eye protection, even if only using LED devices, and emphasize this is absolutely critical with laser devices. Still, long-term safety and efficacy data on this kind of therapy are limited, and research is ongoing.

Product recommendations

Among commercially available devices, Vielight is the most common.