Frequent nappers more at risk of high blood pressure and strokes, study reveals

Frequent nappers run a higher risk of developing high blood pressure or having strokes, a new study has found.

According to research published today in Hypertension, an American Heart Association journal, people who usually nap were 12 per cent more likely to develop high blood pressure and were 24 per cent more susceptible to strokes than those who reported never having a daytime snooze.

Researchers from China found that a higher percentage of frequent nappers were men, and had lower education and income levels than that of sporadic or non-nappers.

Cigarette smoking, daily drinking, insomnia, snoring and being an “evening person” were also more commonly reported as being attributes of regular nap-takers.

Participants in the study younger than 60 years old, who usually napped, had a 20 per cent 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 per cent higher risk of high blood pressure compared to those who reported never napping.

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

The research team used both observational analysis of participants over a long period of time and Mendelian randomisation – a genetic risk validation - to investigate whether frequent napping was associated with high blood pressure and ischemic stroke. The study was the first of its kind to employ both methods.

The study used information from UK Biobank, a large biomedical database and research resource containing anonymised genetic, lifestyle and health information from half a million UK participants.

The database recruited more than 500,000 participants between the ages of 40 and 69 who lived in Britain between 2006 and 2010. They regularly provided blood, urine and saliva samples, as well as detailed information about their lifestyle.

The daytime napping frequency survey occurred 4 times from 2006-2019 in a small proportion of UK Biobank participants.

Wang’s team were careful to exclude records of people who had already had a stroke or had high blood pressure, leaving about 360,000 participants to analyse 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”. About three quarters of participants remained in the same category throughout the study.

The Mendelian randomisation result showed that if napping frequency increased by one category, the risk of developing high blood pressure increased by 40 per cent.

“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,” said Michael A Grandner, director of the Sleep Health Research Program and the Behavioral Sleep Medicine Clinic.

“Poor sleep at night is associated with poorer health, and naps are not enough to make up for that.”

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