Stroke, beware of involuntary and prolonged naps: if they exceed one hour, the risk to the brain increases

Let's face it. For some time now, science has been reminding us how much and how a nap can be useful for 'regenerating' the brain, cleaning it of invisible metabolic waste, rekindling the memory. But now comes a sort of 'countermand' with an invitation to consider the daytime nap (when too long or unwanted) less than ideal in terms of prevention. In short: if you often feel your eyelids getting heavy during the day, you can't give up a long afternoon rest, you doze off for no reason, have even more consideration for the health of your heart, arteries and especially brain. Because statistically, the chances of suffering a stroke are greater in those who take a prolonged nap during the day. Not only that. If the planned and brief nap, say under an hour, could even have a protective effect, when one falls asleep without intending to, the situation is diametrically opposed. And it is worth talking to your doctor for an intelligent 'check' of your cardiovascular risk.

Pointing out how much and how an association (i.e. not a clear cause-effect relationship) might exist between daytime napping and likelihood of stroke is a research study that reviewed a number of studies, evaluating more than 600,000 people (16,000 who had suffered a stroke). Like any meta-analysis, therefore, it may contain different contributions and be difficult to make uniform. But in any case, the survey, published in Sleep Medicine Reviews (first name Radosław Kaźmierski) and conducted by experts from the University of Zielona Góra, Poland, adds interesting pieces to a mosaic of knowledge in the making.

The numbers speak for themselves. First of all, the study reveals that the longer the nap, the greater the risk of stroke. Compared to those who do not sleep during the day, short naps (up to 30 minutes) were associated with a slight increase in risk, while those longer than 90 minutes showed an almost 80 per cent increase. In short: the limit of the hour of daytime sleep seems to represent a sort of watershed: if you exceed this time limit, your chances of having a cerebrovascular accident increase significantly. Not only that. The 'aficionados' of the nap, accustomed to programmed and short naps, do not seem to have particular risk profiles and may even be protected by this habit. But if the nap is unplanned and one suddenly falls asleep unintentionally, remaining in the arms of Morpheus, the dangers grow: those who take long, unplanned naps are almost three times more likely to have a stroke than those who do not sleep during the day. One final important note from the study: the increased risk was observed for all types of stroke - ischaemic, haemorrhagic and subarachnoid - and also among those who simply reported a tendency to nap, regardless of duration.

Let us be clear. The authors of the survey themselves point out that there is no clear cause-and-effect relationship between daytime naps and the risk of cerebrovascular accidents, but rather identify long naps (even more so if unwanted) as possible signs of distress. But the association should not be underestimated, confirming the potential role of sleep disorders on 24-hour well-being. "We know that the need for frequent naps can reveal a night sleep that does not restore - comments Massimo Del Sette, Director of Neurology at the Irccs AOM (Azienda Ospedaliera Metropolitana) in Genoa. Research clearly shows how much and how those who sleep little and/or badly at night have a higher risk of depression, heart attack, type 2 diabetes, and indeed stroke'. The relationship between sleep and stroke, moreover, is one of the most fascinating topics in research on the relationship between hypnic states and neurological problems, and in particular acute cerebrovascular events. 'Disturbed sleep at night due to the presence of obstructive sleep apnoea (what the Anglo-Saxons call OSAS) increases the risk of stroke by about two times,' the expert concludes. It is therefore likely that the presence of disturbed sleep is associated with daytime sleepiness, hence the 'naps', prolonged during the day. Be careful, however: it is not enough to sleep much longer at night to affect the risk of stroke: this increases both for too short night sleeps (under 5-6 hours) and for too long night sleeps (over 8-9 hours)'..