Napping associated with greater risk of strokes, high blood pressure: Study

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More frequent napping was associated with a higher risk for ischemic strokes and high blood pressure, according to a new study.

Researchers in China found that people who usually nap have a 12% higher likelihood of developing high blood pressure and a 24% higher likelihood of having a stroke, according to a news release on their peer-reviewed study published in the American Heart Association‘s Hypertension journal.

Risks in napping were evident in younger participants who were observed: Those who were under 60 and usually napped had a 20% greater risk of higher blood pressure. Among those over 60, there was a 10% greater risk in higher blood pressure.

And for those who increased their napping habits — going from “never” to “sometimes” napping, or from “sometimes” to “usually” napping — the risk of high blood pressure would rise by 40%. Those who napped more were found to be more genetically inclined for a high blood pressure risk.

“These results are especially interesting since millions of people might enjoy a regular, or even daily nap,” said Dr. E. Wang, chair of the Department of Anesthesiology at Xiangya Hospital Central South University and one of study’s authors. 

Researchers gathered data from more than 500,000 participants between 40 and 69 years old who lived in the United Kingdom from 2006 to 2010. 

The participants would regularly provide blood, urine and saliva samples as well as lifestyle information. All participants had their information in the UK Biobank, which contains anonymized genetic, lifestyle and health information.

Researchers said the survey on daytime napping occurred four times between 2006-2019 in a small portion of the participants.

Those who napped most often were men, had lower education and income levels, and reported cigarette smoking, daily drinking, insomnia and snoring. 

More frequent nappers were also reported as being evening people compared to those who reported napping sometimes or never.

Researchers found that about three-quarters of participants stayed in the same napping category throughout the course of the study.

Michael A. Grandner, a sleep expert and associate professor of psychiatry at the University of Arizona, said that napping itself is not a problem.

“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,” Dr. Grandner said.

The study did acknowledge some key limitations.

Data was only collected for daytime napping frequency — not duration — so it didn’t record any information on how or whether the length of nap affects blood pressure or stroke risks. 

The study also acknowledged that it didn’t discover the biological link between daytime napping and its effect on blood pressure regulation or strokes.

All nap frequencies were self-reported and lacked any objective measurements, and all participants were overwhelmingly middle-aged and elderly Europeans, making it hard to generalize the findings.

The study’s full title is “Association of Nap Frequency With Hypertension or Ischemic Stroke Supported by Prospective Cohort Data and Mendelian Randomization in Predominantly Middle-Aged European Subjects.”