Methods: The study group will include twenty-four children and adolescents in various stages of pubertal development. Participants will be categorized into three groups: 1) normal-weight, 2) obese subjects with metabolic syndrome, 3) obese without metabolic syndrome. Melatonin levels will be measured using saliva during the night. Each child will be measured for height, weight, waist circumference and blood pressure. Fasting insulin, glucose and lipid profile will be taken. Each child will fill out questionnaires about depression, sleep quality and television usage.