Canoeist Petter Menning is one of 17 active people who before the Olympics in Tokyo receive extra guidance for better sleep. I thought it sounded really fuzzy with a sleep coach but it was very concrete things that you could turn off or continue with, says Menning. Swimmer Michelle Coleman

Too little sleep has a negative effect on the reaction time, the immune system is weakened and there is a risk of depression. An extra hour of sleep for elite athletes would in many cases give better results than more training, says HC Holmberg, professor of sports science at Mid