What is melatonin -- and should you take it to fall asleep? | Sleeping with Science

Melatonin, a hormone released by the pineal gland, signals nighttime and sleep. While it can be purchased as a supplement, studies show it only slightly improves sleep onset and quality. For better sleep, focus on regular sleep habits, a cool bedroom, evening darkness, morning daylight, and daily physical activity instead of relying on melatonin.