Melatonin is a hormone secreted from the pineal gland located in the brain. Tryptophan, which is an amino acid, converts into serotonin. Serotonin then converts into melatonin. Serotonin is a neurotransmitter associated with depression. In addition to improving sleep, melatonin is a strong antioxidant good for the immune system. As we age, melatonin, DHEA, and human growth hormone decline. The …