(PS10-88) Menopausal hot flashes in sleep disturbance: Does the timing of hot flashes matter?

Abstract Text: Sleep disturbance is common during menopause, with studies estimating that over 50% of women undergoing the menopausal transition report problems with their sleep. Poor sleep is associated with worse quality of life, impaired emotion regulation, and more severe depressive symptoms. Menopause-related sleep disturbance has generally been attributed to hot flashes. However, understanding the association between hot flashes and sleep disturbance is complicated as hot flashes have been defined in multiple ways, including occurrence (does the individual have hot flashes?), frequency (how many hot flashes?), severity (how intense are the hot flashes?), and timing (when do the hot flashes occur?). The purpose of this study is to evaluate various aspects of momentary hot flashes (i.e., frequency, severity, and timing) in association with sleep disturbance. We examined whether evening and/or daytime hot flash frequency and/or severity predicts sleep disturbance (i.e., sleep onset latency [SOL], sleep quality [SQ]). We also evaluated whether nocturnal hot flash frequency and/or severity predicts SQ.

Participants (N=99) completed self-report measures of hot flashes and sleep for seven consecutive days. Participants were prompted to report the number and severity of hot flashes they had in the morning, afternoon, and evening; they also completed a sleep diary each morning to assess for SOL and SQ. We computed the within-subjects effects of daytime (morning + afternoon), evening, and nocturnal hot flash frequency and severity as person mean-centered deviations. We conducted a series of linear mixed effect models regressing sleep outcome onto daytime/evening hot flash frequency/severity, and regressing sleep quality on nocturnal hot flash frequency/severity. Results indicated that evening hot flash severity was significantly associated with SOL (Est = 5.60, SE = 2.48, p < 0.05) and that nocturnal hot flash frequency was significantly associated with SQ (Est = -0.46, SE = 0.05, p < 0.001).

Identifying the specific aspects of hot flashes that predict sleep disturbance is crucial for advancing our understanding of the relationship between hot flashes and sleep, and for determining appropriate treatment targets to improve sleep outcomes. We found that more severe evening hot flashes predicted longer SOL that night, and that more frequent nocturnal hot flashes were associated with worse SQ that night. Our findings suggest that targeting hot flashes that happen at night – both in the evening before bed and nocturnally during sleep – may be especially useful in improving sleep in menopausal women.