Sleep duration and risk of cardiovascular events: The SAVE study

Background and aim: Controversy exists regarding cardiovascular risk in relation to sleep duration. We determined sleep duration and major recurrent cardiovascular event associations in patients with obstructive sleep apnoea and established cardiovascular disease. Methods: Secondary analyses of the international, multicenter, Sleep Apnea Cardiovascular Endpoints trial. Sleep duration was estimated from overnight home oximetry (ApneaLink monitor) used for obstructive sleep apnoea diagnosis. Cox proportional hazards models were used to determine associations of categorized sleep duration (<6 h, 6–8 h (reference), and >8 h) and major cardiovascular outcomes: primary composite of cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and any hospitalization for unstable angina, heart failure, or transient ischemic attack; secondary composite of cardiac and cerebral (stroke/transient ischemic attack) events. Results: Oximetry-derived sleep duration estimates were available in 2687 participants (mean 61.2 years, 80.9% males) who experienced a total of 436 cardiovascular events over a mean follow-up of 3.7 years. Compared to the reference category, sleep duration was not associated with risk of the primary composite cardiovascular outcome (adjusted hazard ratio (HR) 1.00, 95% confidence interval 0.76–1.33, and HR 1.22, 95% confidence interval 0.98–1.52, for sleep duration <6 and >8 h, respectively). However, long sleep was associated with increased cerebral events (HR 1.67, 95% confidence interval 1.17–2.39; P = 0.005) and stroke alone (HR 1.79, 95% confidence interval 1.22–2.63; P = 0.003). Conclusions: Long sleep duration is associated with an increased risk of stroke but not cardiac events in obstructive sleep apnoea patients with existing cardiovascular disease. Clinical trial registration: The trial is registered at ClinicalTrials.gov (NCT00738179).