Daytime activity and risk factors for late-life insomnia.

Laboratory evidence linking exercise with improved sleep quality raises the possibility that the lower levels of physical activity characteristic of older age groups may contribute to late-life insomnia. While support for this hypothesis appears to come from epidemiological surveys, few such studies have distinguished satisfactorily between social and physical activities which differ widely in terms of energy cost and theoretical significance. The present analyses were, therefore, designed to assess the independent influence of physical and social activity levels on the prevalence and natural history of late-life insomnia. Survivors from a nationally representative UK sample (n = 1042) of elderly people originally interviewed in 1985 were reassessed in 1989 (n = 690) and 1993 (n = 410). Detailed assessments of physical and social activities, mental and physical health status, and sleep quality were made at each survey wave. Logistic regression models, adjusted for age, sex and health status, were used to assess relationships between activity levels and the prevalence, remission/persistence, and incidence of late-life insomnia. Lower physical health, depressed mood and lower physical (but not social) activity levels consistently emerged as significant risk factors for prevalent, persistent and incident insomnia. Age was unrelated to insomnia variables in all the cross-sectional models, but did emerge as a significant risk for cumulative 4-8-year insomnia incidence. These findings suggest that, independent of those activities more closely associated with social engagement, higher levels of customary physical activity per se appear to be protective against incident and chronic late-life insomnia.