Melatonin is a hormone produced by the pineal gland in the brain, primarily during the night. It helps regulate the body's sleep-wake cycle, signaling to the body when it is time to sleep. Levels of melatonin typically rise in the evening and fall in the morning, influenced by light exposure. In addition to its natural production, melatonin is available as a dietary supplement. Many people use it to help with sleep disorders, such as insomnia or jet lag. While generally considered safe for short-term use, it's important to consult a healthcare professional before starting any new supplement.