A study from the American Heart Association shows a link between frequent naps and high blood pressure.
- Frequent or habitual daytime naps in adults were associated with a 24% higher risk of having a stroke and a 12% higher risk of developing high blood pressure compared to no nap.
- Experts say that napping, while not unhealthy, could be a sign of poor sleep quality.
- A higher percentage of people who frequently nap were male, had lower levels of education and income, and reported daily drinking, smoking cigarettes, insomnia, snoring, and being an evening person compared to people who reported doing the nap sometimes or never.
- The result of the Mendelian randomization shows that if the frequency of naps increased by one category (from never to sometimes or sometimes to usually), the risk of high blood pressure increased by 40%.
According to new research published on July 25, 2022, in Hypertensiona journal of the American Heart Association, regular naps are associated with higher risks of high blood pressure and stroke.
For the research, Chinese scientists investigated whether frequent naps could be a potential causative risk factor for high blood pressure and/or stroke. This is the first study to investigate whether frequent naps are associated with high blood pressure and ischemic stroke using both long-term observational analyzes of participants and Mendelian randomization – a validation of the genetic risk.
“These findings are particularly exciting because millions of people could benefit from a regular, even daily, nap,” says E Wang, Ph.D., MD, professor and chair of the department of anesthesiology at Xiangya Central South University Hospital. , and the corresponding author of the study.
For the study, the researchers used information from UK Biobank. This large biomedical database and research resource contains anonymised information on the genetics, lifestyle and health of half a million UK participants. Between 2006 and 2010, UK Biobank recruited over 500,000 participants aged 40-69 living in the UK. Participants regularly provided blood, urine and saliva samples, as well as detailed information about their lifestyle. The daytime napping frequency survey was conducted 4 times from 2006 to 2019 in a small proportion of UK Biobank participants.
Wang’s team excluded records of people who had had a stroke or had high blood pressure before the study began. That left about 360,000 participants to analyze the association between napping and first reports of stroke or high blood pressure, with an average follow-up of about 11 years. Participants were divided into three groups based on self-reported napping frequency: “never/rarely”, “sometimes” or “usually”.
The study found:
- A higher percentage of habitual nappers were men, had lower education and income levels, and reported daily drinking, smoking cigarettes, snoring, insomnia, and being an evening person compared to never or sometimes naps;
- People who usually nap were 12% more likely to develop high blood pressure and 24% more likely to have a stroke compared to people who said they never nap;
- Participants under the age of 60 who usually took a nap had a 20% higher risk of developing high blood pressure compared to people of the same age who never took a nap. After age 60, habitual naps were associated with a 10% higher risk of high blood pressure compared to those who reported never taking a nap;
- About three-quarters of the participants stayed in the same nap category throughout the study;
- The result of Mendelian randomization showed that if the frequency of naps increased by one category (from never to sometimes or sometimes to usually), the risk of high blood pressure increased by 40%. Higher napping frequency was linked to genetic propensity for high blood pressure risk.
“This may be because, although taking a nap in itself is not harmful, many people who do may do so because of poor sleep at night. Poor sleep at night is associated with poor health, and naps aren’t enough to compensate for that,” said Michael A. Grandner, Ph.D., MTR, sleep expert and co-author of the American Heart Association’s new Life’s Essential 8 Heart Health Score , which added sleep duration in June 2022 to the 8e metric to measure optimal heart and brain health. “This study echoes other findings that generally show that taking more naps appears to reflect an increased risk of heart health and other conditions.” Grander is director of the Sleep Health Research Program and Behavioral Sleep Medicine Clinic and associate professor of psychiatry at the University of Arizona in Tucson.
The researchers recommend further examination of the associations between a healthy sleep pattern, including daytime naps, and heart health.
Several important limitations of the study should be considered. The scientists only collected the frequency of daytime naps, not their duration, so there is no information on how nap duration affects blood pressure or stroke risk. Additionally, nap frequency was self-reported without any objective measurement, making estimates unquantifiable. Additionally, the research participants were mostly middle-aged and elderly of European ancestry, so the results may not be generalizable. Finally, scientists have not yet discovered the biological mechanism for the effect of daytime napping on blood pressure regulation or stroke.
Reference: “Association of Nap Frequency With Hypertension or Ischemic Stroke Supported by Prospective Cohort Data and Mendelian Randomization in Predominantly Middle-Aged European Subjects” by Min-jing Yang, Zhong Zhang, Yi-jing Wang, Jin-chen Li, Qu-Lian Guo, Xiang Chen and E. Wang, July 25, 2022, Hypertension.
Co-authors are Min-jing Yang, MD; Zhong Zhang, Ph.D., MD; Yi-jing Wang, MD; Jin-chen Li, Ph.D.; Qu-lian Guo, Ph.D., MD; Xiang Chen, Ph.D., MD
The National Key Research and Development Program of China financially supports this research.