Patterns of Sleep Duration and Metabolic Biomarkers Across the Menstrual Cycle

Context: Along the menstrual cycle, associations between inconsistent sleep duration and levels of metabolic biomarkers are uncertain and could involve fluctuations in estrogen concentrations. Objective: To examine associations between patterns of sleep duration and metabolic biomarkers across 2 menstrual cycles within a cohort of premenopausal women. Methods: The BioCycle Study was conducted in New York between 2005 and 2007, enrolling 259 premenopausal women over 2 menstrual cycles. This microlongitudinal cohort study involved intensive data collection including daily sleep diaries and biomarker assessments of leptin, insulin, and glucose at 16 key points timed to menstrual cycle phases. We considered dynamic sleep duration as hours slept 1 night or as mean hours slept during the 2 nights before each biomarker assessment. Variability in habitual sleep duration (ie, reported daily sleep duration) was summarized across both menstrual cycles. Variation in habitual sleep duration was computed using L-moments, a robust version of dispersion, skewness, and kurtosis. To examine associations between patterns of sleep duration and metabolic biomarkers, we fitted a series of linear mixed models with random intercepts and inverse probability weighting. These models were adjusted for potential demographic, lifestyle, health confounders, and menstrual cycle phase. Results: Sleep duration 1 night or 2 nights before clinic visits were not associated with metabolic biomarker measures. However, overall variability (dispersion) in habitual sleep duration was associated with lower mean insulin Homeostatic Model Assessment for Insulin Resistance levels, but not glucose. Moreover, extremely short or long bouts of sleep duration were associated with higher mean levels of leptin, insulin, and Homeostatic Model Assessment for Insulin Resistance. Conclusion: These data suggest that variation in habitual sleep duration along the menstrual cycle may be associated with metabolic function.