A study suggests that increased restless legs syndrome (RLS) severity is associated with subsequent increased risk of stroke.

After considering other known risk factors such as age, smoking, hypertension, and unhealthy diet, results show that increased RLS severity is associated with subsequent increased risk of stroke. There were 161 incident stroke cases during the 6-year follow-up.

“We were surprised at the importance of taking into account RLS severity—it was only severe RLS, not milder RLS, that was associated with increased risk of stroke,” says principal investigator and senior author Xiang Gao, associate professor and director, Nutritional Epidemiology Lab, department of Nutritional Sciences at The Pennsylvania State University in University Park, Pa, in a release.

The research abstract was published recently in an online supplement of the journal Sleep and presented Monday at SLEEP 2015.

The study group comprised 72,916 female registered nurses ages 41-58 years in 2005, free of diabetes, stroke, and pregnancy at the baseline. Information on RLS was collected via a questionnaire that was based on International RLS Study Group criteria.