Abstract The influence of alcohol (ethanol) on sleep was investigated in 10 men. Polysomnography (PS) was recorded on a baseline night (BL-N) and an ethanol (0.8 g/kg) night (Et-N). On visual score rapid eye movement (REM) sleep was reduced, REM latency was prolonged on Et-N as compared to BL-N. Using the fast Fourier transformation method, electroencephalographic power density of REM sleep in δ frequencies band and in the 10–12 Hz range of non-REM sleep were enhanced. REM sleep and non-RJEM sleep changes were prominent in the second-half and first-half of the night, respectively.