Adults who nap during the day could be at risk of high blood pressure and strokes, a study has suggested.
Researchers looked at anonymous medical records of nearly 360,000 people in the UK, asking how often they slept during the day.
Over an 11-year period, they found those who had a nap most days had a 12 per cent higher likelihood of having of high blood pressure.
And the same group was 24 per cent more likely to have a stroke.
American Heart Association
"These results are especially interesting since millions of people might enjoy a regular, or even daily nap," said study author Dr E Wang, from Xiangya Hospital Central South University.
Dr Wang and colleagues studied the records of 358,000 people whose data is stored by biomedical database UK Biobank.
All respondents were between 40 and 69, lived in the UK between 2006 and 2010, and did not have high blood pressure, nor had they suffered a stroke. They regularly provided blood, urine and saliva samples, as well as detailed information about their lifestyle.
Fewer than one in 20 adults said they napped most days, and six in 10 said they did so rarely or never.
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In addition to the main findings above, researchers found:
- A higher percentage of common-nappers were men, had generally lower education and income levels than those who rarely or never napped and reported cigarette smoking, drank alcohol daily, experienced insomnia and were snorers.
- Those under the age of 60 who usually napped had a 20 per cent higher risk of developing high blood pressure. After age 60, usual napping was associated with 10 per cent higher risk of high blood pressure.
The findings were published in Hypertension, an American Heart Association journal.
"Although taking a nap itself is not harmful, many people who take naps may do so because of poor sleep at night," said Dr Michael Grandner, a sleep expert and co-author at the American Heart Association.
"Poor sleep at night is associated with poorer health, and naps are not enough to make up for that.
"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."
Researchers said it was important to note that their findings showed napping was the result of other health factors. They have not yet discovered the biological mechanism for the effect of daytime napping on blood pressure regulation or stroke.
The study's respondents were mostly middle-aged and European.
In the Middle East, hypertension levels also high, ranging from 20 per cent in Iran to 30 per cent in Oman. Across the Gulf, more than a third of adults have hypertension or diabetes, or both, and the average patient with heart disease is almost a decade younger than in the West.
