Women report poorer sleep than men, and oral contraceptive (OC) users appear to experience poorer sleep quality, in particular disrupted sleep, relative to non-users, potentially related to disruption of the circadian rhythm of cortisol. This preregistered study evaluated sleep quality and sleep disruptions and their relationship with cortisol dynamics in naturally cycling (NC) women, OC users and men. In 242 healthy participants from the Cimbi database, we first conducted cross-sectional group comparisons of self-reported sleep quality and sleep disruptions between the groups with linear regression and probabilistic index models, respectively. Second, we examined if the cortisol awakening response (CAR) mediated potential group differences in sleep quality and sleep disruptions. We show no significant differences in sleep disruptions in OC users (n = 31), or in men (n = 124) compared to NC women (n = 87). OC users reported marginally poorer overall sleep quality compared to NC women (padjusted=0.042). This difference was not mediated by the CAR. However, a lower CAR was associated with more sleep disruptions within OC users (-0.138 [-0.238; -0.039], p = 0.006) and with poorer sleep quality in men (0.24 [-0.41; -0.07], p = 0.006), but no associations with sleep were seen in NC women. In conclusion, we find modestly poorer sleep in healthy OC users compared to NC women, but no differences in sleep between NC women and men. Further, our data suggest a coupling between cortisol dynamics and sleep in OC users and men. Prospective studies are necessary to further assess the role of sex/gender differences and OC use in cortisol dynamics and sleep.
Keywords: Cortisol awakening response; Oral contraceptives; Sex; Sex hormones; Sleep.
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