Variability in Sleep Duration and Biomarkers of Cardiovascular Disease across the Menstrual Cycle.

Variability in sleep duration and cardiovascular health have been infrequently investigated, particularly among reproductive-age women. We examined these associations across the menstrual cycle among a cohort of 250 healthy premenopausal women, aged 18-44y. The BioCycle study had collected cardiovascular biomarkers (serum high- and low-density lipoprotein (HDL,LDL), total cholesterol, triglycerides, and C-reactive protein(CRP)) at key time points along the menstrual cycle (follicular, ovulatory, luteal phases). Women also recorded sleep duration in daily diaries. From these data, we computed L-moments, robust versions of location, dispersion, skewness, and kurtosis. We fitted linear mixed models with random intercepts and inverse-probability-weighting to estimate associations between sleep variability and cardiovascular biomarkers, accounting for demographic, lifestyle, health and reproductive factors. Sleep dispersion (any deviation from mean duration) was associated with lower mean LDL for non-shift workers (64%) and non-White women (44%). Skewed sleep duration was associated with higher mean CRP and lower mean total cholesterol. Sleep durations with extreme short and long bouts (kurtosis) were associated with a lower mean HDL, but not mean CRP, LDL or triglycerides. Sleep duration modified associations between sleep dispersion and LDL, HDL, and total cholesterol. Even in young and healthy women, sleep duration variability could influence cardiovascular health.