Abstract
Research has shown that sleep is important to cognition, however, most studies are cross-sectional with small sample sizes. The current study examined the effects of sleep duration and quality on concurrent cognition, and cognition 10 years later. Sleep quality included measures of feeling unrested during the day, waking up during the night or too early in the morning, and trouble falling asleep. Duration was measured via self-reported average hours of nightly sleep. Cognitive measures included factors of episodic memory (EM), executive functioning (EF), and subjective reports of memory (SM). Participants are from the Midlife in the United States (MIDUS) study, a large, national sample of US adults ages 25–75 at baseline. Controlling for age, gender, education, physical and mental health, we found that sleep duration significantly predicted levels of EM and EF, but not SM. Sleep duration also predicted EF 10 years later, controlling for initial levels, but not EM or SM. This was a quadratic relationship; too little or too much sleep was detrimental to EF. Multiple aspects of sleep quality predicted levels of SM, and SM 10 years later, but not EF or EM. This study highlights the relationship between sleep and cognitive changes with aging. Promoting healthy sleep habits throughout adulthood may be a fruitful intervention strategy for buffering age-related declines in cognition. Both sleep duration and quality typically begin declining in midlife and continue to decline into later adulthood; thus a focus on interventions in midlife would likely be beneficial.