Short Sleep Duration and Risk for Strokes

Boston—Researchers found an association between adults of normal weight sleeping <6 hours per night and an increased risk of stroke symptoms, according to an analysis of 5666 people who were part of a large study that has tracked patients for several years.

Megan Ruiter, PhD, the study’s lead author and a postdoctoral fellow in the University of Alabama at Birmingham’s division of preventive medicine, presented the results at the SLEEP meeting. The abstract was titled Short Sleep Predicts Stroke Symptoms in Persons of Normal Weight.

The analysis was part of the REGARDS [Reasons for Geographic and Racial Differences in Stroke] study that examined the factors underlying the excess stroke mortality among African Americans and in the Southeastern United States. The National Institutes of Health’s National Institute of Neurological Disorders and Stroke funded the study.

Between January 2003, and October 2007, the authors enrolled 30,239 adults, all from the United States, who were ≥45 years of age and were African American or white. During the study, the people self-reported their average sleep duration and stroke symptoms.

This analysis included 5666 of the participants who did not have a history of stroke, transient ischemic attack, stroke symptoms, or high risk for obstructive sleep apnea. The authors placed the participants in different groups based on sleep duration: <6 hours, between 6 and 7 hours, between 7 and 8 hours, between 8 and 9 hours, and ≥9 hours.

Dr. Ruiter said the researchers asked the participants the following 2 questions about their sleep: (1) “How many hours of sleep do you usually get at night, or during your main sleep period, on your work days?” and (2) “How many hours of sleep do you usually get at night, or during your main sleep period, on your nonwork days?”

The participants were followed for up to 3 years. Every 6 months, they were asked if they had the following stroke symptoms during the previous 6 months: painless hemibody weakness, painless hemibody numbness, loss of vision in 1 or both eyes, loss of hemifield vision, inability to understand, and inability to express oneself verbally or in writing.

In an unadjusted model, the short sleep (<6 hours) and the long sleep (≥9 hours) groups significantly predicted stroke symptoms. The authors noted the difference was accentuated in adjusted models based on demographic information, Framingham stroke risk factors, depressive symptoms, anxiety, and various health behaviors.

The authors noted there was a significant interaction between sleep duration and body mass index (P=.047).

After stratifying for body mass index (BMI), the authors found a significant association between short sleep duration (<6 hours) and stroke symptoms for the 1651 people with normal BMI (hazard ratio [HR], 2.93; 95% confidence interval [CI], 1.38-6.22; P=.005). They did not find an association with stroke symptoms among overweight or obese patients.

Further, a fully adjusted model for people in the normal BMI group found a strong association between sleep duration of <6 hours and a greater incidence of stroke symptoms (HR, 4.54; 95% CI, 1.75-11.83; P=.002).

“In employed middle-age to older adults, relatively free of major risk factors for stroke such as obesity and sleep-disoriented breathing, short sleep duration may exact its own negative influence on stroke development,” Dr. Ruiter said in a news release. “We speculate that short sleep duration is a precursor to other traditional stroke risk factors, and once these traditional stroke risk factors are present, then perhaps they become stronger risk factors than sleep duration alone.”