The nap, this little sleep during the day, is it good or bad? Is it recuperative? Does it cause insomnia?
Mathilde Fontez, editor-in-chief of the scientific magazine Epsiloon, talks to us today about the benefits of a siesta. How to do it ? How long ? We have entered the idleness period, so we have time to take a nap.
franceinfo: This little nap during the day, is it recuperative? Can it prevent you from falling asleep at night? Is it beneficial or not?
Mathilde Fontez: These are all the questions that epidemiologists, sleep specialists and cardiovascular diseases have asked themselves. Several studies have been published in recent years to try to understand whether or not taking a nap is good for your health. So, of course, we start from the idea that the nap is a rather healthy habit. It is a fairly widespread practice, quite natural. Not just in humans, for that matter, but also in many mammals, or even in flies – flies take naps.
Some researchers have even championed the habit as a public health practice. The siesta is recommended in particular for people who work at night, for operators who make the buses, nurses, pilots, morning radio journalists for example. But when you look closer, the benefits of napping aren’t so obvious.
What large-scale studies show are often cohorts of several thousand people who have been studied, what they show is that beyond a certain duration, napping, on the contrary, tends to be correlated with a greater risk of developing diseases.
Beyond what duration?
A Spanish team has just set the limit at 30 minutes. Less than half an hour, the siesta is beneficial. More than half an hour, it begins to cause more risk of heart rhythm disorders. Another study carried out in China last year shows that long naps of more than an hour are associated with all metabolic diseases: obesity, hypertension, cardiovascular disease. The key point of these studies is to say that the nap does not really compensate for a lack of nocturnal sleep.
When you are in sleep deficit, the nap is not enough to restore the body – this is also valid for the fat mornings of the weekend elsewhere. And even when you’re not sleep-deprived, long naps can cause fatigue, delaying bedtime, throwing circadian rhythms out of whack. It would affect the whole metabolism.
In short, it’s like everything, even the siesta, it must be practiced in moderation. And there is also the last hypothesis: what if the nap was not the cause, but the consequence. And if this need to sleep during the day betrayed diseases that have not yet declared their symptoms? For doctors, the length of naps could be an early warning signal, a sign that something is wrong.