Study finds links between high BP and frequent naps

Napping regularly, according to recent research, is associated with an elevated risk of high blood pressure and stroke.

The study’s findings were published in Hypertension, an American Heart Association magazine. Researchers in China investigated whether taking frequent naps may be a risk factor for high blood pressure and/or stroke. This is the first research to look at whether frequent napping was linked to high blood pressure and ischemic stroke using both observational analysis of subjects over time and Mendelian randomization – a genetic risk validation method.

“These results are especially interesting since millions of people might enjoy a regular, or even daily nap,” says E Wang, Ph.D., M.D., a professor and chair of the Department of Anesthesiology at Xiangya Hospital Central South University, and the study’s corresponding author.

The researchers used data from UK Biobank, a significant biological database and research resource that contains anonymised genetic, lifestyle, and health data from half a million UK individuals. Between 2006 and 2010, the UK Biobank recruited over 500,000 people aged 40 to 69 who lived in the United Kingdom. They supplied blood, urine, and saliva samples on a regular basis, as well as extensive information about their lifestyle. The daytime napping frequency study was conducted four times in a small subset of UK Biobank members between 2006 and 2019.

Wang’s group excluded records of people who had already had a stroke or had high blood pressure before the start of the study. This left about 360,000 participants to analyze the association between napping and first-time reports of stroke or high blood pressure, with an average follow-up of about 11 years. Participants were divided into groups based on self-reported napping frequency: “never/rarely,” “sometimes,” or “usually.”

The study found:

* A higher percentage of usual-nappers were men, had lower education and income levels, and reported cigarette smoking, daily drinking, insomnia, snoring and being an evening person compared to never- or sometimes-nappers;

* When compared to people who reported never taking a nap, people who usually nap had a 12% higher likelihood of developing high blood pressure and 24% higher likelihood of having a stroke;

* Participants younger than age 60 who usually napped had a 20% higher risk of developing high blood pressure compared to people the same age who never napped. After age 60, usual napping was associated with 10% higher risk of high blood pressure compared to those who reported never napping;

*About three-fourths of participants remained in the same napping category throughout the study;

*The Mendelian randomization result showed that If napping frequency increased by one category (from never to sometimes or sometimes to usually) high blood pressure risk increased 40%. Higher napping frequency was related to the genetic propensity for high blood pressure risk.

“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,” said Michael A. Grandner, Ph.D., MTR, a sleep expert and co-author of the American Heart Association’s new Life’s Essential 8 cardiovascular health score, which added sleep duration in June 2022 as the 8th metric for measuring optimal heart and brain health. “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.” Grander is director of the Sleep Health Research Program and the Behavioral Sleep Medicine Clinic and associate professor of psychiatry at the University of Arizona in Tucson.

The authors recommend further examination of the associations between a healthy sleep pattern, including daytime napping, and heart health.