Sleeping badly does gain weight?

Yes! Sleepless nights disrupt the production of melatonin, a hormone that helps us sleep. The lack of it lowers leptin, a hormone responsible for satiety, and increase ghrelin, a substance that awakens hunger. It also decrease the release of serotonin, a neurotransmitter linked to mood and pleasure. Feeling lack of serotonin in our brain suggests "sugar, sugar, sugar!" to restore the energy and offset our need for pleasure. The reasoning is this: if I can not be happy sleeping, I'll be happy eating a chocolate. Lack of sleep can also be linked to stress. And stressed people release more cortisol, a hormone that helps us react perrengues of life - but it also makes us fat.