Taking melatonin about an hour before turning in for the night improved sleep disturbances and sleep-related impairments in patients who had trouble falling asleep at their chosen bedtime and difficulty waking the next day, investigators reported in PLOS Medicine.

The 116 participants in the study were diagnosed with delayed melatonin secretion in dim light, an indicator of abnormal circadian timing related to sleep. They were randomly assigned to take 0.5 mg of fast-release melatonin or a placebo 1 hour before bedtime for at least 5 consecutive nights per week for 4 weeks. All patients were scheduled to try to fall asleep at their desired, rather than habitual, bedtime.