Everybody reacts differently to medicines and supplements, so melatonin may or may not work for you.
Some studies say it could help with jet lag and sleep issues. Other research shows it may let people with insomnia fall asleep slightly faster. It may also help you sleep better through the night, but not necessarily longer.
Still more studies have shown that melatonin doesn't ease sleep problems at all. There's also not enough research to say it helps with any issues not related to sleep.