Melatonin is a hormone produced in the body by the pineal gland and is secreted only at night during the normal hours of sleep. The levels increase rapidly in the late evening, peaking after midnight, and decreasing towards morning. Melatonin helps alliviate fatigue, sleep disturbances, insomnia, and the restless leg syndrome. It also slows ageing, fights disease, and can diminish the effects of jet lag.