Sex differences in age-related changes in the sleep-wake cycle

•The mechanisms underlying age-related differences in sleep are presented.•Knowledge on how age-related differences in sleep interact with sex is reviewed.•Hormonal fluctuations across adulthood interact with sleep and circadian regulation. Age-related changes in sleep and circadian regulation occur as early as the middle years of life. Research also suggests that sleep and circadian rhythms are regulated differently between women and men. However, does sleep and circadian rhythms regulation age similarly in men and women? In this review, we present the mechanisms underlying age-related differences in sleep and the current state of knowledge on how they interact with sex. We also address how testosterone, estrogens, and progesterone fluctuations across adulthood interact with sleep and circadian regulation. Finally, we will propose research avenues to unravel the mechanisms underlying sex differences in age-related effects on sleep.