OBJECTIVE: To investigate the effects of termination of short term melatonin treatment on sleep, health, behavior, and parenting stress in children with delayed Dim Light Melatonin Onset. METHODS: Forty-one children (24 boys, 17 girls; mean age=9.43 years) entered melatonin treatment for 3 weeks and then discontinued treatment by first taking a half dose for 1 week and then stopping completely for another week. Sleep was measured with sleep diaries filled in by parents and with actometers worn by children. Analyses were conducted with linear mixed models. RESULTS: Sleep latency was longer during the stop week compared to the treatment weeks. Sleep start was later and actual sleep time was shorter during the half dose and stop weeks compared to the treatment weeks. Sleep efficiency deteriorated in the stop week. Dim Light Melatonin Onset was earlier after treatment, but this effect disappeared after the stop week. In addition to the effects on sleep, results from questionnaires completed by parents showed that melatonin treatment also had positive effects on children's health and behavior problems and parenting stress. While health deteriorated after treatment discontinuation, the effects on behavior problems and parenting stress remained. Behavior problems at baseline did not influence the effect of melatonin treatment. CONCLUSIONS: This study showed that complete termination of treatment after 4 weeks of melatonin use was too early. However, clinicians may advise a lower dose after a successful treatment trial of several weeks.