Interaction of sleep and emotion across the menstrual cycle.

Menstruating individuals experience an increased risk for sleep and affective disorders, attributed in part to monthly oscillations in sex hormones. Emotional functioning and sleep continuity worsens during the perimenstrual phase of the menstrual cycle. This study examined the interactive effects of sleep, menstrual phase, and emotion in healthy women. Participants (N = 51, 43% Caucasian) aged 18-35 (m = 24 years) completed actigraphy and daily sleep/emotion diaries over two menstrual cycles (m days = 51.29). Diary and actigraphic total wake time at night (TWT) and daily ratings of positive and negative affect were compared across four phases of the menstrual cycle: perimenstrual, mid-follicular, periovulatory, and mid-luteal. Relationships between phase, sleep, and emotion were estimated using multistep hierarchical linear modelling. Mean menstrual cycle length was 28.61 ± 2.69 days. Perimenstrual phase positively predicted anger (p < 0.001) but no other emotions. Additionally, the perimenstrual phase predicted higher rates of TWT, such that diary TWT was 8-16 min longer during the perimenstrual (m = 67.54, SE = 3.37) compared to other phases (p < 0.001). Actigraphic TWT was also increased by 4-7 min (m = 61.54, SE = 3.37) in the perimenstrual phase (p < 0.001). Positive emotions were 0.05-0.10 points lower (p = 0.006-0.02) when TWT was greater in the perimenstrual phase. Greater rates of anger and sleep disruption were seen during the perimenstrual phase compared with other phases. When poor sleep occurred during the perimenstrual phase individuals reported reduced positive emotions. Reducing perimenstrual sleep disruptions may be an important intervention target for those at risk for affective disorders.