In people

When people take melatonin at the right time in the evening, they fall asleep sooner and sleep feels deeper, most clearly in people over 55, whose own melatonin has dropped. Morning alertness is better, not worse, because the clock is set rather than sedated. Travellers adjust to a new time zone in fewer days. Over weeks, the night-time hormone pattern shifts back toward a younger one. Vivid dreams in the first nights are common.