Sleep and 24-H Activity Rhythms and the Risk of Stroke: A Prospective Cohort Study

Introduction: Short and long self-reported sleep durations are associated with a higher risk of stroke, but the association between objective estimates of sleep and 24-h activity rhythms is less clear. We studied the association of actigraphy-estimated sleep and 24-h activity rhythms with the risk of stroke in a population-based cohort of middle-aged and elderly. Methods: We included 1,718 stroke-free participants (mean age 62.2 +/- 9.3 years, 55.1% women) from the prospective, population-based Rotterdam Study. Actigraphy-estimated sleep (total sleep time, sleep efficiency, sleep onset latency, and wake after sleep onset) and 24-h activity rhythms (interdaily stability, intradaily variability, and onset of the least active 5 h) were measured during a median of 7 days (Q1-Q3: 6-7 days). The association of sleep and 24-h activity rhythms with risk of stroke was analyzed using Cox proportional hazards models. Results: During a mean follow-up of 12.2 years (SD: 3.2), 105 participants developed a stroke, of whom 81 had an ischemic event. Although there was no clear association between actigraphy-estimated sleep and the risk of stroke, a more fragmented 24-h activity rhythm was associated with a higher risk of stroke (hazard ratio [HR] per SD increase 1.28, 95% confidence interval [CI] 1.07-1.53). A less stable (HR per SD increase in stability 0.78, 95% CI: 0.63-0.97) and more fragmented (HR 1.28, 95% CI: 1.04-1.58) 24-h activity rhythm was also associated with a higher risk of ischemic stroke. Conclusions: Disturbed 24-h activity rhythms, but not sleep, are associated with a higher risk of stroke in middle-aged and elderly persons. This suggests that unstable and fragmented activity rhythms may play a more prominent role in the risk of stroke than sleep per se.