Adults (18 years and older) Disorder Dosage (milligrams) When Alzheimer's disease (sleep disturbances) 0.5 nightly, 1 hr before bedtime Bipolar disorder (sleep disturbances) 10 nightly by mouth Cancer 10 to 50, most commonly 20 nightly Circadian rhythm entraining (in blind persons) 5 to10 nightly Critical Illness / ICU sleep disturbance 3 nightly Delayed sleep phase syndrome 5 5 hrs before bedtime Depression (sleep disturbances) 5 nightly Headache prevention 5 to 10 nightly Hypertension 1 to 3 short periods of time Insomnia in the elderly 3 to 5 30 - 120 min before bedtime Insomnia of unknown origin (in the non-elderly) 1 to 5 nightly Jet lag 0.1 to 0.5, 5 and 8 Target bedtime at the destination Schizophrenia (sleep disturbances) 2 (not stated) Seasonal affective disorder 0.25 to 5 daily Sleep enhancement in healthy people 0.1 to 6 30 - 60 minutes before bedtime Children (younger than 18 years) There is limited study of melatonin supplements in children, and safety is not established. Use of melatonin should be discussed with the child's physician prior to starting. Disorder Dosage (milligrams) When Circadian rhythm entraining in blind children 2.5 to 10 nightly Preoperative anxiety 0.1, 0.25 or 0.5 per kilogram (of child’s weight?) (not stated) Seizure disorder in children 5 to 10 nightly Sleep disturbances in children with neuro-psychiatric disorders (mental retardation, autism, psychiatric disorders) 0.5 to 10 nightly