Sex differences in the role of sleep on cognition in older adults

Advancing age is associated with decreased sleep quality and cognition. Previous work has shown differences in sleep patterns and perceptions of sleep quality between men and women. However, whether the effects of sleep quality on cognition differ between sexes in older populations remains unclear. We analyzed data from 207 cognitively intact and mildly cognitively impaired participants (89 men and 118 women) aged 60< to estimate the effects of subjective and objective measures of sleep on executive function, verbal memory, and attention using generalized additive models. Objective sleep was measured with the GT9X Link Actigraph, and subjective sleep was measured with the Pittsburgh Sleep Quality Index. We found that women showed optimal executive function with up to about 400 minutes of total sleep time, followed by a decline in performance (p = 0.01). Additionally, a longer total sleep time contributed to lower verbal memory in a linear manner (p = 0.043). In men, there was a marginally significant improvement in executive function with higher sleep efficiency (p = 0.05). Higher self-reported sleep complaints were associated with poorer executive function in cognitively intact women (p= 0.024). Our findings suggest that the effects of sleep quality on cognitive performance differ between older men and women. Furthermore, executive function seems to be the cognitive domain that was most closely related to objective and subjective sleep. This study indicates that interventions focusing on sleep to mitigate the risk of cognitive impairment in older adults may need to be sex-specific.