Is sleep deficit associated with infertility and recurrent pregnancy losses? Results from a prospective cohort study

Biological rhythms, the innate cycle of changes in the body’s physiological functions, are circadian if they have a 24‐hour period. It is known that sleep is a key feature of human circadian rhythm but the relation between sleep and female fertility is largely unknown. This paucity of research is surprising given that circadian rhythms are paramount to human physiology and sleep is related to major female reproductive events. This study was designed to investigate whether there is a difference between the sleep and activity parameters of women with poor reproductive outcome compared with healthy, fertile parous women (comparator group) using subjective (questionnaires) and objective (actigraphy and light exposure) measures. Material and methods A prospective cohort study in a tertiary in vitro fertilization referral center in the UK; composed of three study groups: women diagnosed with recurrent implantation failure, women with recurrent miscarriage (RM) and a comparison group (fertile women without endometrial pathology). Comparison women were selected gynecology patients without endometrial disease (ie perineal complaints or altruistic egg donors). Primary outcome was differences in objective length of sleep in each of the participant groups using actigraphy. Secondary outcomes were subjective sleep quality and quantity, using participant questionnaires, light exposure, and the feasibility of machine learning in activity‐pattern interpretation. Results Women with recurrent implantation failure slept daily on average for 7 hours 35 minutes (± 57 min), 53 minutes less than the comparison group ( P  = .03), although quality of their objective sleep, and quantity of their subjective sleep, were not significantly different. Women with recurrent miscarriage slept less that the comparison women (36 minutes less/night) but more than women with recurrent implantation failure (17 minutes more/night). No difference in light exposure was found between recurrent miscarriage and the recurrent implantation failure and comparison groups. Conclusions This study demonstrates an objective observation of sleep time reduction in women with subfertility, although it is not yet clear if this association is casual. Given our increased understanding of the internal body clock and circadian rhythm on fertility, our observation warrants further investigation.