Gamma waves explained: what the 40 Hz research shows
Written by the Binaura Team · Published 2026-09-02 · Last reviewed 2026-09-02
Gamma is the band with a serious research programme behind it, which makes it the one most worth describing precisely. The human trials exist, they are promising, and they are smaller than almost anyone quoting them admits.
What gamma activity is
Gamma is the fastest of the classically named bands, usually given as 30–80 Hz in the Alzheimer's literature (Chan et al., PLOS ONE, 2022) and as 30–100 Hz or higher elsewhere. It is associated with attention, memory and the binding of information across brain regions.
It is also the hardest band to measure honestly. Gamma sits in the same frequency range as muscle activity from the scalp and jaw, and separating genuine cortical gamma from that contamination is a standing methodological problem. When you see a consumer device reporting your gamma, this is the first question to ask of it.
As with every other band, the edges are conventions rather than biological categories — a review of 184 resting-state studies calls them “historically pre-defined frequency bands” (Newson & Thiagarajan, Frontiers in Human Neuroscience, 2019).
Why 40 Hz became the famous number
Gamma is the one band with a genuinely interesting recent research programme attached, and it is worth describing accurately because the accurate version is neither dismissal nor endorsement.
Work at MIT found that entraining gamma oscillations with light flickering at 40 Hz reduced amyloid load in mouse models of Alzheimer's disease. The approach was named GENUS — Gamma ENtrainment Using Sensory stimuli — and moved into human feasibility work (Chan et al., PLOS ONE, 2022).
Here is the scale of the human evidence, which is the part usually left out. The Phase 2A study was a single-blinded, randomised, placebo-controlled pilot in patients with mild probable Alzheimer's dementia with n = 15, receiving one hour of daily 40 Hz light and sound for three months. The authors' own stated limitation: “the small sample size compounded by some missing data, and we recognize that participants may have exhibited the observed changes without the intervention given the heterogeneity of the rate of progression of AD” — with COVID-19 further interrupting data collection (Chan et al., 2022).
A two-year open-label extension followed five patients and reported no adverse events, with less decline on cognitive scales in three of them. That study had no control arm at all and used matched patients from national research databases instead; plasma samples were available for only two participants (Gamma sensory stimulation in mild Alzheimer's dementia: an open-label extension study, Alzheimer's & Dementia, 2025).
That is the whole human picture at the time of writing: pilot studies in the low tens of patients, promising enough to justify larger trials, and nowhere near the evidence base that the phrase “clinically proven” would require.
What happened when they tested healthy adults
This is the question that matters for anyone reading this page, because you are almost certainly not the population those trials recruited.
A balanced crossover study put 36 healthy adults through 40 Hz auditory stimulation, 60 Hz auditory stimulation, and no stimulation, testing long-term verbal memory and verbal working memory. The result: gamma-band auditory stimulation did not significantly affect recall or working memory (reported in the gamma sensory stimulation literature).
A separate single-session study found robust 40 Hz entrainment in the EEG while the stimulation was running — the brain clearly followed the rhythm — but no significant 40 Hz oscillation afterwards and no significant cognitive improvements, concluding that any effect requires consistent long-term exposure (Lo et al., Journal of Alzheimer's Disease Reports, 2025).
That second finding is the cleanest statement of the gap this whole subject turns on. Entrainment is real and measurable. The cognitive benefit is the part that did not follow. Following a rhythm is not adopting a state — the argument in full is in how sound changes your brainwaves.
A 2026 review adds that later work found either absent entrainment or, in some conditions, increased amyloid burden, with results depending strongly on disease stage, network integrity and stimulation parameters.
What this means for a 40 Hz track
Three things, in order of how often they are ignored.
First, the trials used synchronised light and sound at high intensity for one hour a day, delivered by a purpose-built device — a large LED panel plus a speaker. A binaural audio file on headphones is not that protocol, and results from one do not transfer to the other.
Second, a 40 Hz binaural track is not playing 40 Hz. It is two audible tones whose difference is 40 Hz, and the beat is that difference (Oster, Scientific American, 1973) — see binaural beat frequencies. The GENUS trials used amplitude-modulated sound at 40 Hz, which is a different stimulus again.
Third, the trials recruited patients with diagnosed Alzheimer's dementia. Evidence of a possible effect in a clinical population is not evidence of a benefit in a healthy one, and in healthy adults the memory studies above came back null.
What to do with this
If you find fast, bright, rhythmic audio helps you concentrate, that is a real preference and you do not need a mechanism to justify it — see binaural beats for focus and beta waves explained, the band directly below gamma. What you should not do is buy a 40 Hz track expecting the outcomes reported in dementia pilot studies, or treat it as an intervention for cognitive decline.
If Alzheimer's disease is the actual reason you are reading this, the relevant path is a clinician and, if you want to follow the science, the registered clinical trials — not a consumer audio app. What the evidence actually says covers the wider literature on binaural beats with the same standard applied.
Binaura offers soundscapes and breathing exercises. It is not a treatment for Alzheimer's disease, cognitive decline or any other condition, and makes no health claim. If you are concerned about memory or cognition, talk with a licensed clinician.
Sources
- Chan et al., PLOS ONE, 2022. GENUS feasibility and Phase 2A pilot; gamma given as 30–80 Hz; n = 15 in the randomised pilot; one hour daily for three months. Limitation, in the authors' words: small sample size with missing data, changes may have occurred without the intervention given variable AD progression, and COVID-19 interrupted MRI and EEG collection.
- Gamma sensory stimulation in mild Alzheimer's dementia: an open-label extension study, Alzheimer's & Dementia, 2025. Five patients, two years, no adverse events. Limitation: open-label with no control arm, external database patients used as comparators, and plasma biomarkers available for only two of five participants.
- Gamma sensory stimulation: investigating human brain response to optimize clinical translation, 2026, and the studies it summarises — including the 36-participant crossover finding no significant effect of 40 Hz or 60 Hz auditory stimulation on recall or working memory, and Lo et al. finding robust online entrainment without cognitive improvement after a single session. Limitation: healthy-adult samples in the low tens, and single-session designs cannot detect an effect that requires long exposure.
- Newson & Thiagarajan, Frontiers in Human Neuroscience, 2019. Bands as historically pre-defined conventions. Limitation: a review of heterogeneous resting-state studies.
Related: beta waves explained, how sound changes your brainwaves, and what the evidence says.
How this post was written: it is built from published research rather than from house opinion, and every study behind a number on this page is linked in place, next to the figure it supports, with the limitation the authors themselves stated. If a claim here has no link, it is not a claim we are making. Corrections go to Binaura support.