Melatonin is a widely used supplement. Many people turn to the hormone hoping it will improve their sleep, but do claims of its efficacy have any merit? Clinical evidence suggests that the benefits of melatonin are modest, and it may not help everyone. And there's little to stop supplement makers from selling you snake oil. Reactions explains the chemistry of this popular sleep aid: https://youtu.be/qjUKsW93qRU.