If you have restless legs syndrome (RLS), your risk of heart disease may be doubled, according to a January study from Harvard researchers.

The study included more than 3,400 middle-aged and older men and women, and researchers assessed the participants for RLS and cardiovascular issues such as past stroke or heart attack or angina (chest pain).

They found that those with RLS had more than twice the risk of cardiovascular disease, even after taking issues such as body weight, smoking, diabetes, and blood pressure into account. The association between RLS and cardiovascular disease was strongest in people who had restless legs symptoms at least 16 times a month.

More than 12 million Americans are thought to have RLS, which tends to occur more frequently and become more bothersome in middle age. People with the condition have strange sensations in the legs while they’re lying down and relaxing, and as a result they often have trouble sleeping, leading to fatigue the next day.

If you have restless legs, this research shouldn’t be cause for alarm, since the new study didn’t show that RLS caused heart problems or stroke. However, experts familiar with the condition say that the lack of sleep could contribute to increased blood pressure, which could affect the heart.

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