Associations Between Sleep Efficiency Variability and Cognition Among Older Adults: Cross-Sectional Accelerometer Study

TL;DR

This study found that greater variability in sleep efficiency is linked to poorer cognitive performance in older adults, suggesting sleep consistency may be important for cognitive health.

Contribution

It is the first large-scale study to examine the association between sleep efficiency variability and multiple cognitive functions in older adults using accelerometer data.

Findings

Greater sleep efficiency variability correlates with worse cognitive test scores.

Sleep variability remains associated with lower cognition after adjusting for confounders.

Sleep consistency may be a target for interventions to preserve cognition.

Abstract

Objective: We aimed to determine the relationship between day-to-day sleep efficiency variability and cognitive function among older adults using accelerometer data and three cognitive tests. Methods: Older adults aged 65+ with 5 days of accelerometer data from the National Health and Nutrition Examination Survey (NHANES) who completed the Digit Symbol Substitution Test (DSST), the Consortium to Establish a Registry for Alzheimers Disease Word-Learning subtest (CERAD WL), and Animal Fluency Test (AFT) were included in this study. Associations between sleep efficiency variability and each cognitive test were examined adjusted for age, sex, education, household income, marital status, depressive symptoms, diabetes, smoking habits, alcohol consumption, arthritis, heart disease, prior heart attack, prior stroke, activities of daily living, and instrumental activities of daily living. Results: A total of 1074 older adults were included in this study. Greater sleep efficiency variability was univariably associated with worse cognitive function based on the DSST (per 10% increase, Beta -3.34, 95% CI -5.33 to -1.34), CERAD-WL (per 10% increase, Beta -1.00, 95% CI -1.79 to -0.21), and AFT (per 10% increase, Beta -1.02, 95% CI -1.68 to -0.36). In adjusted models, greater sleep efficiency variability remained associated with lower DSST (per 10% increase, Beta -2.01, 95% CI -3.62 to -0.40) and AFT (per 10% increase, Beta -0.84, 95% CI -1.47 to -0.21) scores but not CERAD WL scores. Conclusions: Targeting consistency regarding sleep quality may be useful for interventions seeking to preserve cognitive function among older adults.