For how we live.
Short courses look well tolerated, but trials rarely run past a few weeks, so long-term safety is untested. Two clearer problems: variable supplement content, and a surge in children's accidental ingestions.
The pooled effect is about seven minutes off the time it takes to fall asleep. The American Academy of Sleep Medicine recommends against it — on evidence it grades as weak in both directions.
A Cochrane review found melatonin reduced jet lag in nine of ten trials. Sleep medicine's own guideline rates it a first-tier option for jet lag disorder. Take it at the wrong hour and it can make things worse.
A network meta-analysis of 41,084 surgical patients over 60 ranked 52 drug interventions. Dexmedetomidine held up after high-risk trials were excluded; almost nothing changed length of stay or mortality.
A systematic review located 19 articles on melatonin in children aged 0 to 6. Trials covered 167 children, all with neurologic conditions. There was no efficacy data for typically developing children.