Sleep and physical frailty in older adults

Abstract

Motivations The relationship between sleep and frailty in older age is complex. Two approaches were employed to advance our understanding of the association between insomnia and physical frailty in old age. First, we hypothesized that insomnia might influence frailty status through a third factor implicated in the complex physiological and biological systems. Second, insomnia might impede the effort, such as physical interventions, made to prevent or delay the progression of frailty. Methods Study 1 employed a cross-sectional design to explore whether physical performance, level of physical activity, and depressive symptoms mediated the relationship between insomnia and physical frailty. Study 2 was a secondary analysis of a cluster randomized controlled trial to test whether the change in frailty status following a 6-month aerobic training or resistance training differed between older adults with and without insomnia. A community-based sample of 390 prefrail and frail older adults were recruited and completed the measures on insomnia symptoms (Pittsburgh Sleep Quality Index) and frailty status (The FRAIL Scale). Two insomnia symptoms, including sleep-onset insomnia and sleep-maintenance insomnia, were studied individually. Results Study 1: The prevalence of sleep-onset insomnia was higher in frail participants than their prefrail counterparts (48% vs. 34%; OR = 1.73; 95% CI 1.09, 2.76; P = 0.02). The association between sleep-onset insomnia and frailty was explained by reduced physical performance (standardized coefficient = 0.11; 95% BCa CI [0.002, 0.233]), but not depression and level of physical activity. Sleep-maintenance insomnia was not associated with frailty. Study 2: Improvement in frailty status in the aerobic training group and resistance training group were comparable to that in the lifestyle education group. There was a significant interaction between physical intervention and sleep-onset insomnia (OR = 4.08; 95% CI 1.12, 14.87; P = 0.033). Physical intervention seemed to promote reversal of frailty among older adults without sleep-onset insomnia (OR = 1.89; 95% CI 0.94, 3.79; P = 0.073). Discussion Insomnia symptoms were prevalent in frail and prefrail older adults. Sleep-onset insomnia was associated with poorer physical performance, which was further linked to a higher risk for frailty in older persons. Furthermore, physical interventions might ameliorate the progression of frailty, but the positive change was subject to the presence of sleep-onset insomnia. Significance The findings highlight the importance of timely assessing and managing insomnia among older adults at risk of frailty. Further development of multicomponent interventions that incorporate both insomnia treatment and physical activity is warranted for the management of frailty for older adults with sleep-onset insomnia.