0048 Investigating the Effects of Consecutive Nights of Pre-sleep Alcohol Use on Sleep Spindle Density and Distribution

Abstract Introduction We previously reported the impact of consecutive nights of alcohol on sleep macrostructure variables. Sleep spindle density and distribution, however, remain unexamined in response to alcohol. This report tests the hypothesis that sleep spindle density will be lower following pre-sleep alcohol and most affected early in the sleep period. Methods Thirty (15F; ages=22-57, mean=33) healthy adult participants took part in a crossover, within-subjects study with two 3-night in-lab conditions: a Mixer + Alcohol condition targeted a BrAC of 0.08 mg/L and a counter-balanced Mixer-only condition; conditions were separated by ≥ 3 days. All drinking ended 1 hour before lights out. Sleep EEG derivations C3-A2 and C4-A1 were submitted to a validated sleep spindle detection algorithm (Ferrarelli, et al., 2007). Sleep spindle density in NREM sleep (#/min; Stages 2-4) was averaged between channels and submitted to a series of linear mixed-effects models. A first, 2x3 model examined the factors beverage and night (Nights 1-3) on NREM spindle density. Next, data were stratified into thirds of the night, with the model repeated for each third. Results A main effect of alcohol on sleep spindle density across the whole night was identified (F(1,145)=5.33, p=.022). Sleep spindle density was lower on Mixer + Alcohol nights (1.6±0.7 spindles/min) vs Mixer-only (1.9±0.5 spindles/min). No effect of Night(1-3) or interaction of beverage and night was observed (p’s>.05). Next, we identified opposing effects of alcohol on sleep spindle density in early vs. late sleep. In the first third of the night sleep spindle density was lower on Mixer + Alcohol nights (0.4±0.3 spindles/min) compared to Mixer-only (0.9 ± 0.3 spindles/min; F(1,145)=8.33, p.05). Conclusion Alcohol use prior to sleep resulted in reduced sleep spindle density early in the night and higher spindle density late in the night. No effects of consecutive nights were observed. These differences add to a growing discussion of the impact that alcohol has on sleep physiology across the night. Support (if any) R01AA025593