0189 Menstrual Cycle Phase and Alcohol Use Interact to Influence Daily Sleep Outcomes

Introduction Rates of heavy drinking are increasing in women at an alarming pace. Studies suggest that although alcohol has an initial sedative effect, it can lead to frequent awakenings. Preliminary studies suggest that women may be more sensitive to alcohol-disrupted sleep than men. Women’s sleep changes across the month due to the impact of cycling hormones, yet studies examining links between alcohol-disrupted sleep and menstrual cycling are scarce. Here, we used daily diary methods to track menstrual cycles, sleep, and alcohol use in normal cycling women. Methods 44, cisgender women, aged 18-45, completed morning and nightly diaries to track sleep/wake behavior, alcohol use, and menstrual cycling for two weeks (N=586observations). Each morning, participants reported bedtime and waketime and the number of minutes it took them to fall asleep, which was used to determine sleep duration and onset latency, respectively. Sleep quality was assessed on a Likert scale of 1=‘very bad’ to 4=‘very good’ and morning ratings of refresh on a Likert scale of 1=‘not at all’ and 7=‘completely’. Prior to sleep, participants indicated if they drank any alcohol, and if so, how many drinks they ingested. We examined the impact of on vs. off menses as well as day in cycle – early-follicular, late-luteal, or periovulatory – on alcohol use and sleep outcomes using linear mixed effects models. Results On average, participants went to bed at 12:18AM, woke up at 7:59AM, slept 8hrs and 17mins, and had sleep onset latencies of nearly 16mins. Participants reported good sleep quality (M=3.14) and feeling relatively refreshed (M=5.14) upon awakening. On menses, drinking was associated with longer sleep onset latencies (r=.216). Off menses, drinking was associated with lower sleep quality (r=-.125) and ratings of morning refresh (r=-.214). On days when women drank alcohol, they also had marginally worse sleep quality (p=.056). Periovulatory vs. early-follicular days were associated with less ratings of morning refresh (p=.019), and a marginal interaction between phase and alcohol suggested that drinking alcohol during the periovulatory phase led to significantly lower feelings of refresh the next morning (p=.076). Conclusion These data suggest that sleep may be more sensitive to alcohol disruption near ovulation in women. Support (if any)