Sleep disturbances are common in adolescents. The etiologies include biological, environmental, and sociocultural factors. The structure of sleep changes during adolescence, and it is easy for adolescents to stay awake. Sleep deprivation causes psychiatric symptoms. On the other hand, many psychiatric disorders cause secondary insomnia. The primary care is sleep hygiene counselling and behavioural therapy. If the sleep disorder is secondary, treatment of the primary disorder is the most important help. The scientific data of pharmacological management of insomnia of adolescent is thin. Melatonin might be worth a try, since there is scientific data of its effectiveness and safety.