Study shows link between short cycles of sleep, stroke and SCI in elderly hypertensive patients

Data presented today at the American Society of Hypertension, Inc.'s 25th Annual Scientific Meeting and Exposition (ASH 2010) demonstrate a link between short cycles of sleep, stroke and silent cerebral infarct (SCI), or "silent strokes," in elderly hypertensive patients. Although data suggest SCI to be more prevalent among patients with a longer duration of sleep, patients who experienced both SCI and short-sleep duration were at the greatest risk of stroke.

"Stroke is extremely debilitating to patients and our healthcare system, therefore, it is important that we learn as much about these events as possible," said lead author of the study, Kazuo Eguchi, M.D., Division of Cardiovascular Medicine, Jichi Medical University School of Medicine in Tochigi, Japan. "These additional data may help direct the focus of future research on stroke in elderly patients with hypertension."

In the study, shorter sleepers tended to be younger and have fewer SCI compared to longer sleepers.
In those patients who did not experience an SCI, there was no difference of the incidence of stroke between the patients with shorter vs. longer sleep time>

Using a multivariable Cox regression analysis, researchers found that:
•Short sleep duration was associated with increased risk of stroke events>•Presence of SCI was associated with stroke events>•Sleep duration less than 7.5 hours was independently associated with stroke risk>•When patients were divided into those who experienced an SCI>

Out of a pool of 1,268 patients with hypertension who received ambulatory blood pressure monitoring, 932 patients were given a brain MRI to assess for SCI. Researchers analyzed those patients using Cox proportional hazard models to calculate hazard ratios (HR) and 95 percent confidence interval of sleep-duration-associated risk for cardiovascular events, controlling for significant covariates. Patients were divided into five groups, according to sleep time. Sleep duration was classified into quintiles.