Melatonin is a chemical your brain produces when it gets dark outside. It is known as the sleep hormone because it tells you when to sleep and when to wake up. Melatonin supplements can help with certain conditions, e.g. jet lag, delayed sleep-wake phase disorder, certain sleep disorders in children, and anxiety before and after surgery. Studies show that supplements are safe and have fewer side effects than many prescription sleeping pills. You can find it in the form of tablets, lozenges and chewing gum.