Sleep Patterns and the Risk of Acute Stroke: Results from the INTERSTROKE International Case-Control Study

Background and Objectives: Symptoms of sleep disturbance are common, and may represent important modifiable risk factors for stroke. We evaluated the association between a spectrum of sleep disturbance symptoms and risk of acute stroke in an international setting.

Methods: INTERSTROKE is an international case-control study of patients presenting with first acute stroke and controls matched by age (+/- 5 years) and sex. Sleep symptoms in the previous month were assessed via a questionnaire. Conditional logistic regression estimated the association between sleep disturbance symptoms and acute stroke, expressed as odds ratios and 95% confidence intervals. The primary model adjusted for age, occupation, marital status and modified-Rankin Scale at baseline, with subsequent models adjusting for potential mediators (behavioural/disease risk factors).

Results: Overall, 4,496 matched participants were included, with 1,799 of participants having experienced an ischemic stroke and 439 an intracerebral haemorrhage. Short sleep (<5hrs: 3.15, 2.09-4.76), long sleep (>9hr: 2.67, 1.89-3.78), impaired quality (1.52, 1.32-1.75), difficulty getting to sleep (1.32, 1.13-1.55) or maintaining sleep (1.33, 1.15-1.53), unplanned napping (1.59, 1.31-1.92), prolonged napping (>1hr: 1.88, 1.49-2.38), snoring (1.91, 1.62-2.24), snorting (2.64, 2.17-3.20) and breathing cessation (2.87, 2.28-2.60) were all significantly associated with increased odds of acute stroke in the primary model. A derived Obstructive Sleep Apnoea (OSA) score of 2-3 (2.67, 2.25-3.15) and cumulative sleep symptoms (>5: 5.06, 3.67-6.97) were also associated with a significantly increased odds of acute stroke, with the latter showing a graded association. Following extensive adjustment, significance was maintained for the majority of symptoms (not difficulty getting to/maintaining sleep and unplanned napping), with similar findings for stroke subtypes.

Discussion: We found that sleep disturbance symptoms were common, and associated with a graded increased risk of stroke. These symptoms may be a marker of increased individual risk, or represent independent risk factors. Future clinical trials are warranted to determine the efficacy of sleep interventions in stroke prevention