Frequent Napping Linked to High Blood Pressure and Stroke Risk, Says New Study

• A new study shows how napping regularly may put you at higher risk for high blood pressure and stroke.
• Compared to people who reported never taking a nap, people who usually nap had a 12 per cent higher likelihood of developing high blood pressure and 24 per cent higher likelihood of having a stroke.
• “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.”

An afternoon nap may seem harmless, but new research suggests that a regular nap schedule may be hurting your heart health.

A study was published in Hypertension that showed that people who often nap have a greater chance of developing high blood pressure and having a stroke. This is the first study to use 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 researchers looked at 358,451 participants free of hypertension or stroke from UK Biobank. They used these participants to analyse the association between napping and first-time reports of stroke or high blood pressure, with an average follow-up report of about 11 years. Participants were divided into groups based on self-reported napping frequency: “never/rarely,” “sometimes,” or “usually.”

In the study, when compared to people who reported never taking a nap, people who usually nap had a 12 per cent higher likelihood of developing high blood pressure and 24 per cent higher likelihood of having a stroke. Researchers also found that participants younger than age 60 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.

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.

About three-fourths of participants remained in the same napping category (never, sometimes, usually) throughout the study. The Mendelian randomisation showed that if napping frequency increased by one category (from never to sometimes or sometimes to usually) high blood pressure risk increased 40 per cent. Higher napping frequency was also related to the genetic tendency for high blood pressure risk.

These results held true even after researchers excluded people at high risk for hypertension, such as those with type 2 diabetes, existing high blood pressure, high cholesterol, sleep disorders and who did night-shift work.

The study concluded that the analyses proved that increased daytime nap frequency may be a responsible risk factor for essential hypertension. The cause and effect relationship of increased nap frequency with ischemic stroke was further supported by both the randomised and observational results.

In a statement, the author of the study Dr E Wang explained that “these results are especially interesting since millions of people might enjoy a regular, or even daily nap.”

“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 sleep expert Dr Michael A. Grandner (he was not involved in the study). "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.”

As with any study, there are some limitations that are important to consider. For example, researchers only collected daytime napping frequency, not duration, so there is no information how or whether the length of nap affects blood pressure or stroke risks. Additionally, nap frequency was self-reported without any objective measurements, making estimates immensurable. The study’s participants were mostly middle-aged and elderly with European ancestry, so the results may not be generalisable. Finally, researchers have not yet discovered the biological mechanism for the effect of daytime napping on blood pressure regulation or stroke, so additional research is required before reaching this conclusion.

So what can you take away from this new research?

Sleep is an essential part of our heart health. If we aren’t getting our quality sleep at night and taking more daytime naps to make up for those lost Zs, our heart health is still taking a toll. To avoid extra risk for hypertension and stroke, make sure you are getting all the quality sleeping hours you need and keeping the naps to a minimum.