People who nap during the day may be doing so because of poor sleep at night, which is associated with poorer health. The study at Banner-University Medical Center in Tucson found that people who typically napped were more likely to develop high blood pressure over time and have a stroke compared with those who never napped.
Individuals younger than age 60 who regularly nap had a higher likelihood of having high blood pressure than individuals without or rare daytime napping. The study, which was published online Monday in Hypertension, an American Heart Association journal, determined that naps up to 90 minutes a day had the greatest benefits.
Sleep experts at Northwestern University Feinberg School of Medicine in Chicago report that napping may increase the risk of heart attack and stroke, even if other factors such as high cholesterol and diabetes are excluded. Dr. Phyllis Zee, director of the Center for Circadian and Sleep Medicine at Northwestern University Feinberg School of Medicine in Chicago, said she thinks the study’s findings highlight the importance for doctors to ask patients about daytime sleepiness and consider how other factors could increase their risk for cardiovascular disease.
Longer naps are worse
A study used data from 360,000 people who participated in the Brigid Study to the greater Biobank, a biomedical database and research resource that tracked UK residents from 2006 to 2010.
A study of people in the UK found that blood, urine, and saliva samples were collected on a regular basis, along with answers to questions about napping. However, the study did not collect information on how long participants napped for and relied on self-reports of napping, a limitation due to imperfect recall. “This study didn’t define what a nap should be,” said Dr. Raj Dasgupta, an associate professor of clinical medicine at the Keck School of Medicine at the University of Southern California. “If you’re going to be sleeping for an hour or two hours, that’s not really a nap. A refreshing power nap that’s 15 to 20 minutes around noon to 2 p.m. is 100% the way to go if you’re sleep deprived,” said Dasgupta, who was not involved in the study. “If you have chronic insomnia we don’t encourage napping because it takes away the drive to sleep at night.”
A study of the habits of people who take naps reveals that many of them smoke cigarettes, drink alcohol, snore, have insomnia and are “evening people,” meaning they go to bed late and wake up late. These factors could all contribute to poor sleep quality, which in turn leads to excessive daytime fatigue and napping during the day. Dr. Dasgupta believes that napping is a warning sign of an underlying sleep disorder in certain individuals. Sleep disorders are linked with an increase in stress hormones, which can lead to obesity, high blood pressure, type 2 diabetes—all risk factors for heart disease.