Melatonin

N-acetyl-5-methoxytryptamine

A darkness signal for timing sleep, not a knockout pill.

Melatonin is the hormone your brain releases as darkness falls to signal that it's time to sleep. Supplements don't sedate you like a sleeping pill; they shift the body's clock, which is why melatonin works best for jet lag and a delayed sleep schedule and less well for ordinary insomnia.