050 Evening Alcohol Consumption and Slow Wave Sleep: Impact on Morning Hippocampus-Dependent Learning across Three Nights

Abstract

Abstract Introduction Numerous studies interrogated the relationship between alcohol and a single night of sleep. Yet, many adults engage in cumulative days of drinking. Previous studies show alcohol on a single night increases slow wave sleep in the first third of night. Similarly, sleep has been associated with the success of daytime learning. Our goal was to investigate across three consecutive nights how evening alcohol use and nighttime sleep are associated with morning learning. Methods 23 adults (11F, mean age 33.5±12 years) completed six nights of PSG monitored sleep. Participants consumed alcohol with a target 0.08 breath alcohol concentration (BrAC) and no alcohol on three consecutive nights in counterbalanced order. Percent of slow wave sleep (SWS%) in the first third of the night was derived. Learning was assessed each morning with distinct stimuli on the Mnemonic Similarity Task (MST). The MST score derived was the Lure Discrimination Index (LDI), defined as the proportion of similar images correctly identified minus the proportion of old images incorrectly identified. Results SWS% during the first third of the night was greater for alcohol nights compared to non-alcohol nights (F(1, 110)=10.891, p=0.01). However, there was no evidence that either night number or the interaction of drink content and night number affected %SWS in the first third of night (all p’s > 0.05). There was a modest decrease in LDI on mornings following alcohol consumption; however, this effect was not significant. In a separate linear mixed-effect model we found no evidence for an effect of night number, drink content, or their interaction on MST LDI scores (all p’s > 0.05). Conclusion Our results indicate that slow wave sleep in the first third of the night is sensitive to evening alcohol consumption. Despite prior literature associating slow wave sleep with next-day learning, we observed no effect of alcohol or night number on morning learning. It is possible that the small sample size contributed to our results. There is little prior research on the cumulative effects of alcohol on sleep and learning; our study adds to this area of research despite the negative findings. Support (if any) R01AA025593