At this point, we should all know that we have to sleep eight hours a night. Less and you work below normal. But what about more? Is it possible to have too much rest?
A new study suggests that actually, sleeping nine hours or more per night could also be detrimental to health. Researchers from around the world collected data on 116,632 people in 21 countries. They were followed for about 7.8 years to determine whether the amount of sleep slept correlated with their overall mortality risk (their risk of death during the study). They published their results in the European Heart Journal, which showed what epidemiologists call a J-shaped curve. The phenomenon refers to a point in a mortality graph where the risk is minimized. In this case, it would be about eight hours of sleep. The more you reduce the number of hours of sleep, the greater the risk of death increases, for a host of reasons, but the risk also increases when you increase the duration of sleep. And they are not the only ones to find J-shape. Other studies have also shown that people who rested at least nine hours each night seemed to have higher mortality rates.
But that does not necessarily mean that more sleep is causing no more death. Sometimes a curve is J-shaped because of another confounding factor.
Think of an adult you know who sleeps 10 hours a day. Is it a healthy person? Probably not. Experts such as Matthew Walker, director of the Sleep and Neuroimaging Laboratory at the University of California, Berkeley, explained how various chronic diseases and conditions could lead to more sleep, while increasing risk of deceased. He discusses studies like this one in his book, Why we sleep, in which he points out that "if you explore these studies in detail, you will learn that the causes of death in people who sleep at least nine hours include infections (for example, pneumonia) and immune-activating cancers" . no one to sleep anymore, he points out, and so "the illusion created is that too much sleep leads to an untimely death, rather than the more valid conclusion that the disease was too much, despite all the contrary efforts of the extension beneficial sleep. "
The researchers who led this most recent study were well aware of this criticism and have therefore made impressive efforts to try to prevent the confounding factor of the disease. They tried to eliminate people with symptoms suggestive of an underlying disease, as well as those who had already had a diagnosed illness, and achieved similar results. This could be a sign that there is really something in sleeping more that is unhealthy for us. But it is also important to note that even these researchers note that "this study or other observational studies do not conclusively prove causality". Observational studies are very useful for analyzing large populations on which you can not perform detailed sleep analyzes, but simply. not able to draw conclusions as to whether one factor caused another.
To understand this, you need to do some kind of randomized study. This would involve prescribing groups to sleep a certain amount for many years and following them to see what happened, which is probably not feasible. Apart from that, researchers will need to find a plausible mechanism by which sleep increases the risk of death. Cigarettes, for example, have never been prescribed to people who have subsequently been followed in lengthy randomized studies. Scientists have had to make other smarter experiments to understand the impact of cigarette components on the human body and use this evidence to draw conclusions from observational data.
However, so far, Walker writes that no "biological mechanism showing that sleep is harmful has been discovered". That does not mean they will not be in the future – we may find a mechanism. It's just that right now it's unclear how 9.5 hours of sleep could negatively impact a person.
The statistics also suggest that even more Americans should worry about not getting enough sleep than enough. A 2013 Gallup poll showed that 40 percent of Americans normally slept six hours or less per night, while only five percent got more than nine hours. Part of the problem with chronic sleep deprivation is that you do not realize how deprived you are of sleep while you are sleep deprived. The researchers tested this by monitoring people in the sleep labs and making them sleep eight hours a night, then six hours more per night, and asking them to do the same test after each. When asked how they thought they would have them after only six hours of sleep, people responded that they had done well, probably as well as they did when they were doing it. they are fully recharged. In fact, they did a lot worse. They just did not realize it.
So, if you are one of those who claim that they only need six hours, do not use this study to prove that it is just as bad to get as well a lot of sleep. The jury still does not know how much an excess of sleep could hurt you, but it is certainly clear how harmful it is to be deprived of sleep chronically. Aim for eight hours each night, no matter what time you think you need. And if you regularly sleep more than nine or ten hours a night, consult a doctor to make sure you do not have an underlying disorder or sleep disorder. You can be perfectly fine, but you never know.