According to an evaluation published within the April 2025 issue, getting nine or more hours of sleep each night is related to worse cognitive performance, an effect that's stronger in individuals with depressive symptoms. Alzheimer's and Dementia.
Researchers examined sleep duration and cognition in 1,853 adults aged 27 to 85 (average age 50, 57% female) who had not been diagnosed with dementia or had suffered a stroke. Participants were classified into 4 groups: no depressive symptoms and no antidepressant use; no depressive symptoms and antidepressant use; antidepressant use and no depressive symptoms; and depressive symptoms in addition to antidepressant use.
Those who slept nine or more hours per night were more likely than participants who slept between six and nine hours per night to attain worse on tests of cognitive performance assessing elements equivalent to memory, visual-spatial skills and executive function. These associations were stronger in individuals with depressive symptoms no matter their antidepressant use. Long sleepers were also more prone to report symptoms of depression. Many experts recommend healthy adults get seven to eight hours of sleep each night. The results of this study don't prove that less sleep will prevent or treat depression or other mental health disorders, however the findings may help scientists higher understand the connection between sleep and mental health.
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