100 Effect of 3 consecutive nights of alcohol on sleep variables: Preliminary report

Abstract

Abstract Introduction The effects of a moderate dose of alcohol one hour before bedtime on sleep have not often been studied nor is the effect across nights well known. We therefore sought to test whether such effects as sleep disruption, increased early-night slow wave sleep (SWS), and reduced early-night REM sleep would be sustained across nights. Methods Twenty-five healthy participants (13 male; ages 22–69 yr, mean = 35) reporting moderate drinking kept a fixed sleep schedule (8–9 h TIB, confirmed by actigraphy) for about one week before two 3-night sleep studies in the lab separated by ≥ 3 days. Participants drank either mixer alone or a beverage containing alcohol targeting a breath alcohol content (BrAC) of 0.08% in a counter-balanced order over 45 min ending 1 hr before lights out. Sleep was scored using Rechtschaffen & Kales (1968) rules in 30-sec epochs. Mixed-effects models examined beverage type, study night, and the interaction of beverage and night for 13 variables: sleep efficiency, sleep latency, REM latency, and full-night percent of Stage 1, Stage 2, SWS, and REM sleep; and percent of SWS and REM sleep by thirds of night. Results A significant effect of Night was seen for sleep efficiency (F(2,120)=3.79; p=.025) and sleep latency (F(2,120)=5.19;p=.007), both lower on N1, as well as for REM latency, longer on N1 (F(2,120)=6.52;p=.002). REM latency was longer with alcohol (F(1,120)=14.16; p<.000) and no interaction was apparent. St2% was higher (F(1,120)=4.47; p=.037) and REM% lower (F(1,120)=4.41; p=.038) with alcohol, whereas overnight SWS% was unaffected; none showed an effect of night or an interaction. SWS% in the first (F(1,120)=10.51; p=.002) and second thirds (F(1,120)=8.27; p=.005) of the night was higher with alcohol and unaffected in the last third. REM% in the first third alone was higher with alcohol (F(1,120)=10.71; p=.01). Conclusion These findings show only modest effects of pre-sleep alcohol consumption (targeting 0.08% BrAC) on subsequent sleep in healthy drinkers, with no evidence of a cumulative impact across three nights. We aim to increase the sample size and examine effects on next-day cognitive function in subsequent analyses. Support (if any) R01AA025593