Within- and between-person associations of sleep characteristics with daily cognitive performance in a community-based sample of older adults.

OBJECTIVES

Few studies have examined daily effects of sleep on cognition. This analysis examined both between-person and within-person associations of actigraphic sleep with daily cognitive performance ascertained via ecological momentary assessments.

METHODS

Data are from community-residing, dementia-free older adults in the Einstein Aging Study (mean age 77.2 ± 4.7, 67.3% female, 47% non-Hispanic White, and 40% non-Hispanic Black) who were free of dementia. Over 16 days, participants wore wrist actigraphs and completed cognitive assessments six times daily using study-provided smartphones and completed overnight pulse oximetry. Brief cognitive tasks assessed four domains of cognitive function. Multilevel linear mixed-effect models assessed associations of sleep characteristics with cognitive performance. Data were aligned such that models addressed the relationship between a day's sleep parameters and the next day's cognitive performance, adjusted for demographics, depression, cardiovascular comorbidity, and sleep-disordered breathing.

RESULTS

In adjusted models, between-person associations showed that higher average wake after sleep onset (WASO) was associated with slower average processing speed, worse working memory, and worse visual memory binding. Within-person effects showed that an individual's processing speed was slower than usual on days following a night with greater-than-usual WASO. Sleep duration, timing, or naps were not associated with any of the cognitive tests.

CONCLUSIONS

Using ambulatory assessments in real-world environments, the results demonstrate short-term effects of sleep fragmentation (WASO) on processing speed the next day in dementia-free older adults. Better understanding short-term effects might identify individuals who may benefit from early interventions to prevent long-term cognitive decline.