Gamma waves (above 30 Hz)
When is gamma seen?
Gamma activity is linked with integrating sensory information and with tasks that need attention. Gamma measured at the scalp is easily contaminated by muscle activity, which makes it hard to interpret.
Listening to a beat at this band's rate has not been shown to move the brain into that band; a weak EEG response may appear at the beat rate, but it is not known to change mental states reliably.
Gamma on headphones
Binaural perception weakens above 30 Hz, so isochronic or monaural methods are used at high rates. Gamma sessions show a disclaimer strip and a note about ringing in the ears.
What does the evidence say?
The brain may show a weak response at the beat frequency; this response has not been shown to reliably change mental state.
▲ C · Preliminary/mixed evidence- What do we know?
- The brainstem responds at the two tone frequencies, while a measurable EEG response at the beat frequency can occur in the cortex; for binaural beats it is weaker than for monaural beats and weakens further under white-noise masking.
- What don't we know?
- In a review of 14 EEG studies, only 5 were consistent with the entrainment hypothesis and 8 contradicted it. It has not been shown that this response reliably changes mental state; in one study mood did not change at all.
40 Hz is a gamma rhythm studied with light-and-sound devices. This session is not a treatment.
■ D · Insufficient evidence- What do we know?
- 40 Hz stimulation is studied in Alzheimer's research because of animal findings; human studies have used light, sound or both. A meta-analysis of 11 controlled studies found no significant change in cognitive function, and tinnitus was reported more often with stimulation. A review of 62 sound-only studies found that brain findings from animal models were not consistently replicated in humans; some studies reported positive changes in cognitive measures.
- What don't we know?
- The large sham-controlled HOPE study (673 participants) completed on 17 August 2026 (primary completion 22 June 2026); as of 3 October 2026 no results are posted or published. The effect of 40 Hz binaural beats heard through headphones on attention is also inconsistent: one study found none, a small one found better general attention. In the earlier OVERTURE trial (76 people, 6 months), the light-and-sound device did not separate from sham on the primary clinical measure; most authors work for the company that makes it.
Evidence levels and sources come from the database; the article adds no new claims. Evidence methodology
Frequently asked questions
- What did the large 40 Hz study find?
- As of the date on the evidence card, the results of the large sham-controlled study had not been announced. The evidence library will be updated when they are published.
Listen and try
Last updated: 1 October 2026 · This article is for information only; it is not medical advice.