Melatonin is an amine hormone produced mainly by the pineal gland in mammals and humans. The main biological effects relevant to the human body are improvement of sleep quality, antioxidant, and regulation of immune function. 1. Melatonin can regulate the body’s circadian and seasonal rhythms, helping to extend the body’s sleep time and improve sleep quality. 2. Melatonin has an antioxidant effect, it can directly scavenge free radicals and enhance the activity of antioxidant enzymes in the body. 3. Melatonin can regulate the body’s immune function, melatonin is a kind of neuroimmunomodulator, can help improve the body’s immune function. 4. Melatonin can regulate the body’s energy metabolism, reduce the accumulation of abdominal fat induced by a high-fat diet, and also lower blood sugar and blood lipids.