Melatonin is a hormone that helps regulate sleep-wake cycles. It is available as an over-the-counter supplement and is commonly used as a sleep aid. Melatonin supplements can be effective for jet lag and certain sleep disorders, but their efficacy for general insomnia varies among individuals. Melatonin is generally considered safe for short-term use when taken at appropriate dosages. However, it's important to note that melatonin supplements can cause side effects and interact with certain medications. If you're considering melatonin as a sleep aid, it's best to consult a healthcare provider before use.