Sleep duration and incident frailty: The Rural Frailty Study.

BACKGROUND

The association between sleep duration and frailty remains unconclusive since most of the studies have been cross-sectional. Therefore, this study aimed to analyze the association between sleep duration, sleep complaints, and incident frailty.

METHODS

A community-based cohort study from rural areas in Mexico with 309 older adults aged 70 and over. Data from waves two and three of the Rural Frailty Study were used. We operationalized the Fried frailty phenotype to describe prevalent and incident frailty at two consecutive waves. Sleep duration was classified as: ≤ 5 h, 6 h, 7-8 h, and ≥ 9 h; and the self-reported sleep complaints as a dichotomous variable. Analyses were performed using Poison regression models.

RESULTS

The average age was 76.2 years and 55.3% were women; the incidence of frailty was 30.4%; 13.3% slept ≤5 h, and 38.5% ≥ 9 h. Compared with the group that slept 7-8 h, the risk of frailty at 4.4 years of follow-up was significantly higher among those who slept ≤5 h (adjusted RR 1.80, 95% CI: 1.04-3.11) and among those who slept ≥9 h (adjusted RR 1.69, 95% CI: 1.10-2.58). Sleep complaints were not associated with incident frailty (adjusted RR 1.41, 95% CI: 0.94-2.12).

CONCLUSIONS

Our results show that short and long sleep duration are associated with the incidence of frailty. Studies that objectively evaluate sleep duration are needed to clarify whether meeting the recommended hours of sleep decreases frailty incidence.