['The effect of exercise on sleep-disordered breathing is unknown. While diet and weight loss have been shown to reduce the severity of sleep-disordered breathing, it is unclear whether exercise has an independent effect.', 'A population-based longitudinal epidemiologic study of adults measured the association between exercise and incidence and severity of sleep-disordered breathing. Hours of weekly exercise were assessed by 2 mailed surveys (1988 and 2000). Sleep-disordered breathing was assessed by 18-channel in-laboratory polysomnography at baseline and at follow-up.', 'Associations were modeled using linear and logistic regression, adjusting for body mass index, age, sex, and other covariates. Hours of exercise were associated with reduced incidence of mild (odds ratio 0.76, P=.011) and moderate (odds ratio 0.67, P=.002) sleep-disordered breathing. A decrease in exercise duration also was associated with worsening sleep-disordered breathing, as measured by the apnea-hypopnea index (β=2.368, P=.048). Adjustment for body mass index attenuated these effects.'] Is exercise associated with a reduced incidence of sleep-disordered breathing?