Nocturnal and next-day effects of ethanol and basal level of sleepiness



Five healthy young men (mean age 25.6 years) consumed ethanol (0.8 g/kg producing breath ethanol concentration (BEC) of 0.06 per cent on average 30 min post-consumption) and placebo at 2200–2230 h after 4 and 8 h in bed (TIB) the previous night. Standard sleep recordings were collected from 2300 to 0700 h. The next-day latency to sleep onset was tested at 1000, 1200, 1400 and 1600 h and divided attention performance and hangover symptoms were assessed 30 min after each latency test. The 4 h TIB increased sleep efficiency, but did not interact with the effects of ethanol. Ethanol altered sleep staging. In analyses of ethanol effects by halves of the night, ethanol increased percentage stage 3/4 sleep in the first half and increased percentage stage 1 sleep in the second half. The following day, mean daily sleep latency (MSLT) was reduced and mean divided attention tracking errors were increased with ethanol. Ethanol effects (mild) on the hangover questionnaire were detected only on the 0800 h assessment.