Many symptoms of poor sleep may be linked to an increased risk of acute stroke, according to the case-control INTERSTROKE study.

Stroke patients were more than twice as likely to report shorter sleep (less than 5 hours; OR 3.15, 95% CI 2.09-4.76) and longer sleep (more than 9 hours; OR 2.67, 95% CI 1.89-3.78) in the preceding month compared with matched controls. Shorter and longer sleep duration were each tied to both ischemic stroke and intracerebral hemorrhage (ICH), reported Christine McCarthy, MSc, of University of Galway, Ireland, and co-authors.

Other sleep characteristics associated with stroke were long unplanned naps, poor quality of sleep, and sleep apnea and its symptoms of snorting, snoring, and breathing cessation while sleeping, according to the study published in Neurology.

“Given that individual sleep disturbance symptoms were common and associated with increased odds of stroke, interventional studies in patients with high sleep disturbance burden, and in those with individual sleep symptoms, should be considered a priority research target in the global effort to reduce stroke incidence,” said McCarthy in a press release.

“With these results, doctors could have earlier conversations with people who are having sleep problems. Interventions to improve sleep may also reduce the risk of stroke and should be the subject of future research,” she added.

Sleep has direct ties to cardiovascular health. The American Heart Association added sleep to their “Life’s Essential 8” cardiovascular health checklist last year, alongside factors such as BMI, blood glucose, blood pressure, cholesterol, smoking, diet, and exercise.

McCarthy and colleagues noted that while there is evidence supporting an association between obstructive sleep apnea (OSA) and stroke, links between stroke and some other sleep disorder symptoms are not as well documented.

“Prior epidemiologic studies have evaluated the association of these sleep parameters and stroke, but the methodology and results are inconsistent,” they wrote. “Most studies have incompletely measured all relevant sleep domains, which precludes a thorough understanding of their independent contribution. Certain symptoms, such as nocturnal awakening and snorting, have also been interrogated infrequently as potential independent risk factors.”

INTERSTROKE is a large international case-control study of patients presenting with a first stroke and controls without previous stroke history. In the present analysis, 1,799 patients experiencing ischemic stroke and 439 experiencing ICH were recruited within 72 hours following hospital admission. They were subsequently age- and sex-matched to controls without stroke for a total study cohort of 4,496 individuals.

On average, patients in the stroke cohort were age 63 years and women accounted for 42% of the group. By ethnicity, 37% of each cohort analyzed was European, 26% were South Asian, 18% were Chinese, 5.6% were Latin American, 5.5% were Black African, 3.3% were Arabic, and 2.9% were another Asian ethnicity.

Some associations were seen between ethnicity and sleep duration, where participants with South Asian ethnicity and living in South Asia were associated with stroke as the result of shorter sleep. However, this was not significant in participants with Chinese ethnicity and residence in China.

Participants had responded to a questionnaire about their sleep history in the previous month, which was a major limitation of the study, the authors acknowledged.

Moreover, sleep quality or OSA symptoms were not measured using previously validated tools. The short time frame of the study, coupled with lack of adjustment for fluctuating sleep patterns in an individual over time, may have also affected results.

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