40 Hz

40‑Hz Light During Sleep Evokes Gamma Activity Without Disrupting Sleep: A Feasibility Step Toward Noninvasive Dementia Therapies

A proof‑of‑concept polysomnography study in 30 healthy adults shows that 40‑Hz visual stimulation during wakefulness, NREM2/3 and REM sleep reliably evokes gamma-band EEG responses without measurable sleep disruption, supporting feasibility

Gamma (40 Hz) Sensory Flicker Shows Promise for Insomnia but Needs Controlled Trials