Napping could lead to high blood pressure, stroke, study suggests

DALLAS - A new study suggests napping on a regular basis could increase the risk of developing high blood pressure and stroke.

The results were published in Hypertension, an American Heart Association journal.

Researchers in China studied the link between napping and heart health. They used information from UK Biobank, a database, to obtain health information from half of million residents in the United Kingdom. They also recruited more than 500,000 participants between 40 and 69 years old who lived in the U.K. between 2006 and 2010.

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The participants regularly provided blood, urine and saliva samples, as well as detailed information about their lifestyle. 

Records of people who previously had a stroke or high blood pressure were excluded before the start of the study. That left researchers with 360,000 participants to study the association between napping and first-time reports of stroke and high blood pressure.

Participants were divided into groups based on self-reported napping frequency: "never/rarely," "sometimes," or "usually."

According to the American Heart Association, results showed:

• 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.

"These results are especially interesting since millions of people might enjoy a regular, or even daily nap," E Wang, the study’s corresponding author, said in a news release. 

Researchers recommend further studying the link between a healthy sleep pattern and heart health.

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However, researchers pointed out several limitations of the study. They only collected daytime napping frequency, not duration — meaning there’s no information on how the length of a nap can affect heart health. 

Furthermore, nap frequency was self-reported with many of the participants being mostly middle-aged and elderly with European ancestry. Scientists also have not yet discovered the biological link between daytime napping on blood pressure regulation or stroke.

This story was reported from Los Angeles.