Melatonin is the hormone most directly responsible for regulating the body's sleep-wake cycle, also known as the circadian rhythm. Produced primarily by the pineal gland in the brain, melatonin levels naturally rise in the evening as it gets dark, signaling to the body that it's time to wind down and prepare for sleep. Light exposure — especially blue light from screens — can suppress melatonin production, which is why sleep experts often recommend limiting screen time before bed. Melatonin doesn't knock you out like a sedative; rather, it guides the body toward a state of restfulness, helping you fall asleep more naturally. It's also available in supplement form, often used by people dealing with insomnia, jet lag, or shift work. However, long-term supplementation should be approached with caution, as natural production can be affected. Overall, melatonin is the body’s internal sleep signal, orchestrating your natural rhythm and supporting restorative, quality sleep.