Sleep disorders have been widely reported in obese individuals. Previous studies have shown that together with an increase in obesity prevalence, so does sleep duration in children and adolescents decrease. By contributing to energy imbalances, hormonal changes occurring with reduced sleep quality may cause weight gain and obesity. Current evidence shows that short sleep duration has effects on body weight and weight gain. Compared to individuals sleeping for a normal duration, insulin sensitivity is lower in those who sleep less. Lack of sleep increases the desire for food and has a direct effect on physical activity. Further studies are required to determine the contribution of sufficient sleep to obesity treatment.