Does lack of sleep make you put on weight?

Sleeping well is also training: it is at night that the body recovers and rebuilds itself.

The study

Researchers at the University of Pennsylvania welcomed more than 200 healthy adults to their laboratory. Some of them were only allowed to sleep 4 hours a night (from 4 a.m. to 8 a.m.) for five nights; the others slept normally, up to 10 hours. Everyone could eat freely.

The result: the sleep-deprived participants gained more weight in just a few days. They ate more, especially at night, with a preference for fattier foods.

Why?

Lack of sleep disrupts appetite hormones, in particular ghrelin, which makes you hungry, and leptin, which signals fullness. Staying up late also means more opportunities to snack.

Tips for runners

• Aim for 7 to 9 hours of sleep a night, at regular times.
• Avoid very intense sessions late in the evening if they stop you from falling asleep.
• Limit screens in the hour before bed.
• After a big session, a proper dinner helps you recover… and avoids night-time cravings.

A popular myth along the way: we often hear that "the hours before midnight count double". This has not been proven. What matters is the length and regularity of sleep.

Sources

• Spaeth A. M., Dinges D. F., Goel N., "Effects of experimental sleep restriction on weight gain, caloric intake, and meal timing in healthy adults", Sleep, 2013. See on PubMed
• Assurance Maladie (French national health insurance), advice for sleeping well, ameli.fr.