Sleep, cognition and aging

Sleep, Cognition, and Normal Aging: Integrating a Half-Century of Multidisciplinary Research.
Scullin MK, Bliwise DL.
Perspect Psychol Sci. 2015 Jan;10(1):97-137. 

Sleep is implicated in cognitive functioning in young adults. With increasing age there are substantial changes to sleep quantity and quality including changes to slow wave sleep, spindle density, and sleep continuity/fragmentation. A provocative question for the field of cognitive aging is whether such changes in sleep physiology affect cognition (e.g., memory consolidation). We review nearly a half-century of research studies across 7 diverse correlational and experimental literature domains, which historically have had little crosstalk. Broadly speaking, sleep and cognitive functions are often related in advancing age, though the prevalence of null effects (including correlations in the unexpected, negative direction) in healthy older adults indicates that age may be an effect modifier of these associations. We interpret the literature as suggesting that maintaining good sleep quality, at least in young adulthood and middle age, promotes better cognitive functioning and serves to protect against age-related cognitive declines.