Light & photobiomodulation
Transcranial Photobiomodulation
Graded on: cognition (limited human evidence).
Grade C: human trials exist, but they are small, mixed or not yet repeated. This is not a finding that it does not work. How to read a grade →
Transcranial photobiomodulation shines red or near-infrared light on the head. It is studied for memory and thinking problems that come with age. A review found early studies that did not agree well with each other. The most promising work so far is in animals. It has not been tested for preventing dementia or in healthy adults.
A letter describes the human evidence, not the product, the manufacturer, or the intervention's worth.
See the full evidence record →Graded on Cognition (limited human evidence).
Why this gradeGrade C, small or unreplicated trials. The reasoning, and what the grade does not cover.
Grade C on cognition. A systematic review A review that searches for every study on a question using a method set in advance, then assesses them together. and meta-analysis A study that pools the numbers from several trials into one combined estimate. of photobiomodulation for age-related cognitive impairment found early, heterogeneous trial evidence (Gao et al., 2023; PMID PubMed ID: the permanent number the US National Library of Medicine gives a published paper. Each one links to that paper's record on PubMed. 37843594); the strongest recent work remains preclinical.
WHAT THIS GRADE DOES NOT COVERdementia prevention, healthy adults, and any specific device or wavelength, none of which the cited review graded, and the preclinical findings, which carry no letter.
A grade describes the human evidence for a named use. It is not advice, and it is not a judgment on any individual prescription. How the letters are decided →
The evidence, in fullOne paper, linked to its PubMed record.
Gao et al. (Lasers in Medical Science, 2023; PMID 37843594): systematic review of photobiomodulation for age-related cognitive impairment. Grade C: early, heterogeneous trial evidence.
A validated cognitive battery (MoCA, CNS Vital Signs) at baseline and 8 weeks. For depression applications, use the PHQ-9 or HAMD-17 at baseline and 8 weeks. Device parameters (wavelength, power output, treatment site, session duration) at every session: transcranial PBM device specifications vary enormously and the literature is not yet protocol-standardized.
Evidence notes: meta-analysis, not independently replicated The same finding reproduced by a separate research group. A result seen once can be chance or bias; a replicated one is harder to explain away.
Endpoint The outcome a trial measures to decide whether the treatment worked, such as heart attacks, blood pressure or a symptom score. graded: Cognition (limited human evidence) (functional)
Last reviewed: July 2026
Educational use only · Not medical advice · EBL grades published human evidence and does not recommend treatment. Stopping a prescription is a decision for your physician.
Primary evidenceOne paper, linked to its PubMed record.
Gao et al. (Lasers in Medical Science, 2023; PMID 37843594): systematic review of photobiomodulation for age-related cognitive impairment. Grade C: early, heterogeneous trial evidence.
Products carry no letter. The letter belongs to the therapy as the trials studied it, and no trial tested these products unless the entry says so. Listed alphabetically; payment does not affect order.
Transcranial plus intranasal photobiomodulation headset, marketed for memory and cognition and sold as a general wellness device. 810 nm, with a 10 Hz (Alpha) and a 40 Hz (Gamma) pulse mode.
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