DALLAS — Naps can feel refreshing, but they may not be all that healthy for you. Chinese researchers have found that napping frequently leads to a higher risk for high blood pressure and stroke.
Researchers from Xiangya Hospital Central South University analyzed whether napping regularly could have a link to poor cardiovascular health. This is the first such study to use both observational analysis of participants over a long period of time and Mendelian randomization — a genetic risk validation — to investigate whether frequent napping can raise blood pressure and ischemic stroke risk.
“These results are especially interesting since millions of people might enjoy a regular, or even daily nap,” says Dr. E. Wang, the study’s corresponding author and professor and chair of the Department of Anesthesiology at Xiangya Hospital Central South University, in a media release.
Researchers collected data of more than 500,000 participants from the UK Biobank — a large biomedical database and research resource containing anonymous genetic, lifestyle, and health information. The participants were between the ages of 40 and 69 and lived in the United Kingdom between 2006 and 2010. They provided blood, urine, and saliva samples, and also details about their lifestyle. Study authors add the daytime napping frequency survey gathered information four times between 2006 and 2019 from a small proportion of UK Biobank participants.
Researchers rejected records of participants who already had a stroke or high blood pressure before the start of the study, leaving about 360,000 people to analyze. The team divided participants into groups based on self-reported napping frequency, including “never/rarely,” “sometimes,” or “usually.”
Napping may be even worse for younger adults
The study found that people who usually nap have a 12-percent higher likelihood of developing high blood pressure and a 24-percent higher risk of having a stroke in comparison to those who rarely or never nap. Participants under 60 who frequently nap have a 20-percent higher risk of developing high blood pressure compared to people of the same age who never nap. Of those over the age of 60, napping displayed a link to a 10-percent higher risk of developing high blood pressure.
Researchers also say the Mendelian randomization results showed that if napping frequency increased by one category — from “never” to “sometimes” or “sometimes” to “usually” — the risk of high blood pressure onset increased 40 percent.
“This may be because, although taking a nap itself is not harmful, many people who take naps may do so because of poor sleep at night. Poor sleep at night is associated with poorer health, and naps are not enough to make up for that,” explains Dr. Michael Grandner, director of the Sleep Health Research Program and the Behavioral Sleep Medicine Clinic and associate professor of psychiatry at the University of Arizona. “This study echoes other findings that generally show that taking more naps seems to reflect increased risk for problems with heart health and other issues.”
The study is published in the journal Hypertension.