how long does melatonin last? Melatonin is a hormone naturally produced by the pineal gland in the brain that regulates sleep-wake cycles. It is commonly used as a supplement to aid with sleep-related issues. The duration of melatonin's effects can vary from person to person based on factors such as individual metabolism and the dosage taken. Generally, the effects of melatonin last for about 4 to 8 hours after ingestion. It's important to note that melatonin is not a sedative but rather a sleep regulator, so its effectiveness may vary depending on the underlying cause of sleep disturbances. As with any supplement, it is advisable to consult a healthcare professional before using melatonin, especially for long-term use or in combination with other medications.