Sleep and Cognitive Performance From Teens To Old Age: More Is Not Better

Objectives: To determine the interaction of age and habitual sleep duration in predicting cognitive performance in a large sample of participants aged 15 to 89 years. Methods: This study is a cross-sectional analysis of performance data gathered between January 2012 and September 2013. First-time players ( N = 512 823) of three internet cognitive training games measuring processing speed, working memory, visuospatial memory, and arithmetic participated in the study. Results: Performance was based on a measure of speed and accuracy for each game. The relationship between performance and self-reported habitual sleep duration was examined in the sample as a whole and across 10-year age groups starting at age 15 and ending at 75 and older. Performance peaked at 7 h of sleep duration for all three games in the sample as a whole, and the decrements in performance for sleep durations greater than 7 h were either comparable or greater in the youngest as compared to the oldest age groups. Conclusions: These findings challenge the hypothesis that deteriorating cognitive performance with long sleep duration is driven by medical comorbidities associated with aging. Further, these data are consistent with an optimal dose model of sleep and suggest that the model for the homeostatic recovery of cognitive function as a function of sleep duration should incorporate a curvilinear decline with longer duration sleep, indicating that there may be a cost to increased sleep. Replication and further research is essential for clarifying the sleep duration-cognition relationship in youth and adults of all ages.