Sleep, Cognition, and Normal Aging

Abstract

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.

Sleep deficits but no metabolic deficits in premanifest Huntington's disease

“…Sleep is of upmost importance in life, with multiple links to cognition52 and metabolism 53. In manifest HD, disturbances have been reported in all 3 of these areas, but have not been systematically studied in patients prior to motor disease onset.…”

Hippocampal activity mediates the relationship between circadian activity rhythms and memory in older adults

“…It is possible that individual variations in CARs in older adults may reflect systemic changes associated with low cognition (Tranah et al, 2011;Scullin and Bliwise, 2015). Since disrupted circadian rhythms, which naturally occur with increased age (Huang et al, 2002;Neikrug and Ancoli-Israel, 2010), are also related to poor memory function, monitoring the consistency of CARs over time may be an important predictor of age-related cognitive decline.…”

“…In longitudinal studies, older women who had more variable CARs were more likely to show cognitive decline 5 years later (Walsh et al, 2014), or in some cases, neurocognitive disorders such as mild cognitive impairment (MCI) or dementia (Tranah et al, 2011). Since these studies included broad and often insensitive measures of cognition in very old women (80s) with health problems (Scullin and Bliwise, 2015) little is known about whether disrupted CARs in healthy older individuals contribute to lower memory function.…”

Do Older Adults Need Sleep? A Review of Neuroimaging, Sleep, and Aging Studies

“…One of the most pronounced behavioral and physiological changes with aging is sleep [1]. With increasing age, adults report greater frequency of nighttime awakenings, waking too early without being able to go back to sleep, increased daytime napping, and advanced circadian phase [2].…”

“…By contrast, chronological age was inversely related to REM duration, N2 duration, and N3 duration (slow wave sleep). Interestingly, in rodent models, older mice show greater slow wave activity than younger mice [8], and some human subjects researchers argue that N3 only declines with aging because EEG amplitude declines (guidelines dictate that slow waves be scored only if amplitude is > 75 mV) [1]. However, in studies of aging humans, quantitative EEG analyses have demonstrated that the incidence, frequency, slope, and density of slow waves are altered in older age [9, 10].…”