Highlights
– 40‑Hz visual stimulation (VS) delivered during NREM and REM sleep produces frequency‑specific gamma-band EEG responses (SSVEP) comparable across sleep stages and wakefulness.
– In 30 healthy participants, nocturnal 40‑Hz VS increased 40‑Hz spectral power without objectively or subjectively degrading sleep beyond first‑night effects.
– Findings support feasibility for nocturnal gamma entrainment as a scalable experimental tool and a candidate noninvasive intervention for dementia, while highlighting the need for longer, disease‑targeted trials.
