Abstract
INTRODUCTION: We investigated whether depression modified the associations between sleep duration and cognitive performance. METHODS: We examined the associations between sleep duration and cognition in 1853 dementia-and-stroke-free participants (mean age 49.8 years, [range 27-85]; 42.7% male). Participants were categorized into four groups: no depressive symptoms, no antidepressants; depressive symptoms without antidepressant use; antidepressant use without depressive symptoms; and depressive symptoms and antidepressant use. RESULTS: Long sleep was associated with reduced overall cognitive function (β ± standard error = -0.25 ± 0.07, p < 0.001), with strongest effects in those with depressive symptoms using (-0.74 ± 0.30, p = 0.017) and not using antidepressants (-0.60 ± 0.26, p = 0.024). Weaker but significant effects were observed in those without depressive symptoms (-0.18 ± 0.09, p = 0.044). No significant associations were observed in participants using antidepressants without depressive symptoms. DISCUSSION: Associations between sleep duration and cognitive performance are strongest in individuals with depressive symptoms, regardless of antidepressant use. Future research should elucidate underlying mechanisms and temporal relationships. HIGHLIGHTS: Sleeping ≥ 9 hours/night was associated with worse cognitive performance. This association was stronger among those with depression. Long sleepers were more likely to report symptoms of depression. Sleep may be a modifiable risk for cognitive decline in people with depression.