It may be. Recent studies have suggested an association between 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.
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.
One explanation may be that sleep duration affects hormones regulating hunger — ghrelin and leptin — and stimulates the appetite. Another contributing factor may be that lack of sleep leads to fatigue and results in less physical activity.
So now you have another reason to get a good night's sleep.