JMIR Publications

ABSTRACT

Background:

Disturbed sleep patterns are common among older adults. Numerous epidemiological studies suggest that sleep disturbances may be risk factors for both physical frailty and cognitive impairment. However, evidence for the relationship between sleep duration and cognitive frailty in older adults is lacking.

Objective:

The objective of our study was to examine the associations of sleep duration and its changes with the future risk for cognitive frailty.

Methods:

We analyzed data from the 2008-2018 waves of the Chinese Longitudinal Healthy Longevity Survey. Cognitive frailty was rendered based on the modified Fried frailty phenotype and Mini-Mental State Examination. We categorized sleep duration into short (<6 h), moderate (6-9 h), and long (>9 h) based on self-reports at baseline (i.e., the 2008 wave). We also defined the change in sleep duration based on the 2008 and 2011 waves data. Logistic regressions were used to examine the association between sleep duration and cognitive frailty at baseline. Cox proportional hazards models were performed to assess the relationships of sleep duration and its change with incident cognitive frailty during follow-up. Restricted cubic splines were plotted to explore the non-linear cross-sectional and longitudinal associations between sleep duration and cognitive frailty.

Results:

Among 11,303 participants, 1,298 (11.5%) had cognitive frailty at baseline. Compared to participants who had moderate sleep duration, the odds of having cognitive frailty were higher in those with long sleep duration (odds ratio [OR] =1.71, 95% confidence interval [CI] =1.48-1.97, p<0.001) after adjusting for age, sex, and education. Restricted cubic spline analysis showed a J-shaped non-linear cross-sectional association between sleep duration and cognitive frailty (p for non-linear <0.001). During a median follow-up of 6.7 years among 5,201 participants who were not cognitively frail at baseline, 521 (10.0%) developed cognitive frailty. A higher risk of cognitive frailty was observed in participants with long sleep duration at baseline (hazard ratio [HR] =1.30, 95% CI =1.06-1.59, p=0.013) or with an increase in sleep duration between 2008 and 2011 (HR =1.04, 95% CI =1.00-1.08, p=0.028) after adjusting for covariates.

Conclusions:

Long sleep duration was associated with cognitive frailly in older Chinese adults. Maintaining moderate sleep duration might potentially prevent older adults from developing cognitive frailty.