Recent studies have suggested an association between lack of sleep (or sleep duration) and weight gain. Sleeping less than five hours — or more than nine hours — a night appears to increase the likelihood of weight gain.
Sleep deprivation affects the brain in a way that makes you want to eat more and not process food efficiently. It sparks a vicious cycle where you are left feeling tired, slowing your metabolism and playing tricks with your hormones.
In one study, recurrent sleep deprivation in men increased their preferences for high-calorie foods and their overall calorie intake. In another study, women who slept less than six hours a night or more than nine hours were more likely to gain 11 pounds (5 kilograms) compared with women who slept seven hours a night. Other studies have found similar patterns in children and adolescents.
Snacks: Your body has no energy and thinks you’re hungry. Science says getting less sleep than needed makes the body produce higher peaks of endocannabinoid, a lipid in the bloodstream that’s responsible for making eating feel so much more enjoyable.
Less exercise: The more sleep-deprived you are, the more lethargic you feel, and the less you will exercise. Going back to a sedentary lifestyle will inevitably result in weight gain, especially if you’re eating more.
More carb eating: Tired people tend to reach for foods that are high on bad carbs. After all, you are just looking for something to feel better.
Sleep duration affects hormones regulating hunger — ghrelin and leptin — and stimulates the appetite. Another contributing factor is that lack of sleep leads to fatigue and results in less physical activity.