Long sleep duration is associated with lower cognitive function among middle-aged adults—the Doetinchem Cohort Study

Publication date: Available online 21 September 2017
Source:Sleep Medicine
Author(s): Sandra H. van Oostrom, Astrid C.J. Nooyens, Martin P.J. van Boxtel, W.M. Monique Verschuren
ObjectiveIn older adults, both short and long sleep duration are associated with lower cognitive function, suggesting an inverted U-shaped association between sleep duration and cognitive outcomes. This study examined whether sleep duration is associated with changes in cognitive function in a middle-aged population.MethodsIn the Doetinchem Cohort Study, the cognitive function of 2970 men and women aged 41–75 years at baseline (1995–2007) was examined 2–3 times, with 5-year time intervals. Global cognitive function and the domains memory, information processing speed, and cognitive flexibility were assessed. In multivariable linear regression models, change in self-reported sleep duration was studied in association with the level and change in cognitive function. In a subsample of the population (n = 2587), the association of sleep duration and sleep quality with cognitive function was studied.ResultsSleep duration of 9 hours and more was statistically significantly associated with lower global cognitive function (p < 0.01), memory (p = 0.02), and flexibility (p = 0.03), compared to a sleep duration of 7 or 8 hours. Among adults feeling frequently not well rested, both short and long sleep duration were associated with a lower speed of cognitive function. An inverted U-shaped association between sleep duration and cognitive function was observed for speed, flexibility, and global cognitive function. Sleep duration was not associated with change in cognitive function.ConclusionMiddle-aged adults with long sleep duration had a lower cognitive function.



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