Sleep characteristics in association with risk of sporadic anovulation among eumenorrheic women.

Few studies have evaluated sleep characteristics, including social jetlag, with ovulatory dysfunction, which may be an indicator of subfertility and poor metabolic health. Our objective was to evaluate whether sleep characteristics, including sleep duration, chronotype, social jetlag, sleep latency, nocturnal awakenings, and shift work, were associated with risk of anovulation among eumenorrheic women. Participants had a history of pregnancy loss and regular menstrual cycles, but no history of infertility. Typical sleep characteristics were self-reported at baseline. Participants were followed up to the cycle of conception or up to six menstrual cycles. Fertility monitor data and reproductive hormone concentrations were used to assess anovulation. We used generalized estimating equations with log-Poisson distributions to estimate relative risks (RR). The study is registered at clinicaltrials.gov (NCT00467363). Sleep duration, social jetlag, sleep latency, and nocturnal awakenings were not associated with anovulation. Later chronotype was associated with greater anovulation risk (3^rd vs. 2^nd tertile RR: 1.33, 95% CI: 1.05-1.68; per 1-hour increase RR: 1.05 95% CI 1.00-1.11). The RR for rotating work was 1.14 (95% CI: 0.90-1.46) and for night shift work was 1.22 (95% CI: 0.98-1.52). These results suggest that later chronotype and potentially shift work may be related to menstrual cycle dysfunction.