The Day-to-Day Bidirectional Association of Sleep Difficulties with Affect in Postmenopausal Women

Postmenopausal women are at elevated risk for sleep difficulties and changes in positive affect (PA; energy, interest, etc.) and negative affect (NA; anger, stress, etc.) due to numerous factors, including vasomotor symptoms (VMS). In the general population, there is evidence for a day-to-day bidirectional association between sleep difficulties and affect, such that sleep difficulties predict next day affect and affect predicts next night sleep difficulties. However, this association has not been examined in postmenopausal women, a population susceptible to both sleep difficulties and changes in affect. Therefore, we examined the day-to-day bidirectional association between sleep difficulties and affect in postmenopausal women, and further examined if the relationship differed by the presence of VMS. Participants were enrolled in MsBrain I. Both sleep difficulties and affect were assessed over a 72-hour period at home. Sleep difficulties were assessed via a wrist accelerometer and sleep parameters of interest included total sleep time (TST), sleep efficiency (SE), and wake after sleep onset (WASO). Affect was assessed via ecological momentary assessment. Participants were prompted four times per day on a handheld device to rate how strongly they currently felt each emotion (PA: energetic, interested/involved; NA: angry/irritated, nervous/anxious, and stressed). Total PA and total NA scores were calculated from each survey response and a daily average total PA score and a daily average total NA score was calculated using responses to each survey. VMS were assessed over 24-hours using a sternal skin conductance monitor. Women with objectively measured VMS were labelled as Flashers and women without VMS were labelled as Non-Flashers. Associations were evaluated using mixed-effects models with a random intercept for participant and autoregression process of order one. All models controlled for age, race, years of education, income, marital status, night shift work, sleep medication use, and anxiolytic medication use (Model 1). Depressive symptoms (Model 2) and 24-hour VMS frequency (Model 3) were added as covariates in a hierarchical manner. Participants included 247 postmenopausal women (average age = 59.27, 81.38% White, 77.73% Flashers) with two or more days of concurrent sleep and affect monitoring and 24-hours of valid VMS monitoring. Sleep difficulties predicted next day affect such that moderate TST, higher SE, and lower WASO predicted higher next day PA. Sleep difficulties were unrelated to next day NA. Affect predicted next night sleep difficulties such that higher PA predicted shorter TST and lower WASO. PA did not predict next night SE and NA was unrelated to next night sleep difficulties. VMS status did not moderate the day-to-day bidirectional association between sleep difficulties and affect in all but one case. In that case, moderate TST predicted higher next day PA in Non-Flashers and TST was unrelated to next day PA in Flashers. All associations in Model 1 persisted in Model 2 and Model 3. Findings support a day-to-day bidirectional association between sleep difficulties and PA in postmenopausal women, with better sleep associated with higher next day PA and higher PA associated with changes in next night sleep. In all but one case, this association did not differ by the presence of VMS. These results suggest that targeted therapies for sleep improvement (e.g., cognitive behavioural therapy for insomnia, etc.) may enhance next day positive emotions and targeted practices for increasing positive emotions (e.g., yoga, etc.) may alter next night sleep in postmenopausal women with and without VMS.