Researchers warn good night sleepers who feel the need to also take long naps during the day: this habit may be associated with a higher cardiovascular risk.
In many countries, napping is considered a healthy habit, but is this belief really true? It all depends on night-time sleep patterns, suggests a study conducted by researchers at the Research Centre of the Institut universitaire de cardiologie et de pneumologie de Québec. This indicates that for people who sleep six or more hours a night, the need for long naps during the day could be a sign that a doctor’s consultation is required. To reach this conclusion, scientists collected lifestyle data from 116,632 people in 21 countries over eight years.
For example, they found that the risk of serious cardiovascular events or death depended on a combination of night-time sleep and nap time. Their study, published by the European Heart Journal, reports that cardiovascular risk increases when total daily sleep time deviates from the 6-8 hour window. Thus, people who sleep less than 6 hours daily seem slightly more at risk, about 9%, than those who sleep 6 to 8 hours. For people who sleep 8 to 9 hours, 9 to 10 hours or more than 10 hours, the risk increases by 5%, 17% and 41% respectively compared to average sleepers.
“A marker of undiagnosed disease”
In addition, nap duration has no effect on cardiovascular risk in people who sleep less than 6 hours per night. On the other hand, for people who sleep more than 6 hours a night, this risk increases with the length of the night: it is 30% higher for people who take a nap of one hour or more a day. “For people who sleep less than 6 hours a night, napping seems to be a compensatory mechanism for lack of sleep. For those who sleep a lot at night, fatigue during the day can be a marker for undiagnosed disease,” says Paul Poirier, the study’s lead author.
For researchers, this discovery is important because while sleep is discussed with patients with sleep apnea and hypertension, it is not necessarily discussed with other patients. “Perhaps wrongly,” admits the cardiologist, who concludes: “Patients should therefore make sure to mention their sleep problems to their doctor. “According to the National Institute of Sleep and Vigilance, there are two types of naps to adopt depending on the context. The flash nap lasts less than 5 minutes and improves memory and attention but does not have real sleep while the typical nap lasts between 15 and 20 minutes and only has light slow sleep.