Abstract
OBJECTIVE: The objective of this study was to investigate whether older adults who have a particularly long sleep duration are likely to exhibit physical frailty, similar to those with a particularly short sleep duration. DESIGN: Cross-sectional study. SETTING: The National Center for Geriatrics and Gerontology - Study of Geriatric Syndromes. PARTICIPANTS: A total of 9,824 older adults (mean age: 73.6 ± 5.5 years, 4,812 men and 5,012 women) met the entry criteria for this study. MEASUREMENTS: We divided the participants into three groups according to self-reported sleep duration (Short: ≤6 h, Mid: 6.1-8.9 h (control), Long: ≥ 9 h). Physical frailty was characterized based on the criteria from the Cardiovascular Health Study. Multinomial logistic regression analysis was performed to evaluate the effect of sleep duration on physical frailty by sex. RESULTS: Among all participants, the prevalence of physical frailty was higher in the Short (10.5%) and Long (17.9%) groups than in the Mid (7.4%) group (p < 0.001). Multinomial logistic regression analysis showed that both Short and Long groups had a significantly higher odds ratio (OR) for physical frailty than the Mid group [Short: OR 1.53, 95% confidence interval (CI) 1.26-1.87; Long: OR 2.39, 95% CI 1.90-3.00], even after adjusting for age, educational level, number of medications, body mass index, Mini Mental State Examination score, current smoking and alcohol habits, self-perceived health, and medical history. CONCLUSION: Both long and short sleep durations were associated with physical frailty. Further studies are required to confirm the effect of sleep duration on the incidence or worsening of physical frailty in older adults.