Asked by: Kathryn Friel, Cambridge
Some studies suggest that people who sleep more than nine hours have an increased chance of suffering illness or accident. But it isn’t clear whether this is caused by too much sleep, or if it’s simply that people predisposed to become ill are also more likely to spend longer in bed – for example because they are depressed.
In any case, this is for people that routinely oversleep. Catching up on lost sleep at the weekend doesn’t do you any harm by itself, but it may not be enough to repair damage caused by inadequate sleep during the week. A 2013 study at Pennsylvania State University College of Medicine found that catching up on lost sleep reduced the levels of stress hormones in their blood. But it didn’t improve their performance in tests that measured concentration.