Melatonin is a hormone made by the pineal gland. That’s a pea-sized gland found just above the middle of your brain. It helps your body know when it’s time to sleep and wake up.
Normally, your body makes more melatonin at night. Levels usually start to go up in the evening once the sun sets. They drop in the morning when the sun goes up. The amount of light you get each day — plus your own body clock — set how much your body makes.