Jet lag sucks. The only thing worse than falling asleep at 3pm is waking up at 4am, exhausted, and not being able to sleep.
Melatonin is a partial solution for jet lag. It's a pineal hormone that triggers sleepy time. The problem with jet lag is your ordinary circadian rhythm is on a 24 hour cycle, so until you adjust you're melatonin-deficient at your new local bedtime. But take a melatonin pill or two and bam, you're asleep. Without a sedative.
Because of insane FDA laws melatonin is available without a prescription, but it has a very strong effect, at least on me. I don't make a habit of taking it regularly.