Healthy sleep habits are protective against adverse health outcomes, but it
is unclear how strongly sleep intraindividual variability is associated with
cognitive function among older adults. In this study we aimed to examine how
accelerometer-derived intraindividual variability in sleep duration,
efficiency, onset timing, and offset timing is associated with cognition using
cross-sectional data from the 2011-2014 waves of the National Health and
Nutrition Examination Survey (NHANES). Cognition was assessed by creating a
composite measure derived by summing z-scores from the Digit Symbol
Substitution Test (DSST), Consortium to Establish a Registry for Alzheimers
Disease Word-Learning subtest (CERAD-WL), and the Animal Fluency Test (AFT). A
final cohort of 2508 older adults aged 60+ with at least three days of
accelerometer wear time who completed all three cognitive tests were included
in this study. After centering all sleep intraindividual variability metrics
and adjusting for demographic factors, the presence of diabetes, depressive
symptoms, and measures of functional independence, we found that increased
intraindividual variability in sleep onset timing was associated with worse
cognition (Beta, -0.12; 95% CI, -0.19 to -0.05), as was increased
intraindividual variability in sleep efficiency (Beta, -0.12; 95% CI, -0.20 to
-0.05), and increased intraindividual variability in sleep duration (Beta,
-0.10; 95% CI, -0.17 to -0.03). This study suggests that sleep guidance aimed
at preserving cognition among older adults could be revised to include a focus
on sleep consistency regarding onset timing, quality, and duration.Comment: Typo corrected in the abstrac