Are you a frequent napper? A new study has found that frequent napping could be a risk factor for stroke and high blood pressure.

Several studies in the past pointed out that napping helped reduce daytime sleepiness and boost learning and performance. It also improved alertness and reaction time, per some findings.

But a new study published in Hypertension, a journal produced by the American Heart Association, found a link between frequent napping and stroke and high blood pressure.

The researchers combined observational analyses with Mendelian randomization and used genetic markers to determine whether a risk factor can contribute to a particular disease. They also analyzed data from the U.K. Biobank, which recorded genetic and health data from more than 500,000 participants ages 40-69 living in the United Kingdom between 2006 and 2010. Those who already had a stroke or suffered hypertension when the study began were excluded from the results.

The researchers found that participants who napped in the daytime more frequently increased their hypertension risk by 12%, stroke risk by 24%, and the risk of ischemic stroke (the most common type of stroke caused by a blood clot preventing blood and oxygen from reaching an area of the brain) by 20%. Meanwhile, those who sometimes napped increased hypertension risk by 7%, stroke risk by 12%, and the risk of ischemic stroke by 9%.

Participants younger than 60 who frequently napped also had an increased chance of developing hypertension than those who didn’t take naps. Meanwhile, the percentage dropped to 10% in participants older than 60 who usually napped.

All the participants who napped in the daytime were mostly male, non-European, less educated, had a lower income, and had a higher body mass index and waist-hip ratio.

The study authors were aware of the limitations of their study since only the frequency and not the length of naps was considered. Additionally, the participants in the U.K. Biobank were a fairly homogenous group.

According to Dr. E. Wang, an author of the study and professor and chair of the department of anesthesiology at Xiangya Hospital Central South University, the participants were “predominantly middle-aged Europeans who might not be generalizable to other racial groups.”

Lastly, the researchers pointed out that daytime napping, in general, was not the problem since it also has some benefits.