melatonin

Melatonin signals the body that night has arrived and helps initiate sleep; it is not a reliable way to keep you asleep through the night. For healthy adults who are not older, supplementation has shown only small average sleep benefits, and high doses raise concerns because melatonin also affects other hormone systems. 1 2

• Sleep initiation, not maintenance: Melatonin can help you fall asleep, but it does not help maintain sleep across the night. 3
• Small average benefit in healthy adults: A meta-analysis found an average increase of 3.9 minutes in total sleep and 2.2% in sleep efficiency. 4
• Potential hormonal effects: High melatonin levels may affect reproductive hormones and gonad function; melatonin also has roles in bone mass and puberty timing. 5 6
• Label accuracy varies: Tests of commercial supplements found melatonin amounts substantially below or above label claims. 7
• Light regulates melatonin: Light suppresses melatonin; getting natural light during the day and keeping light dim or red at night can support its daily rhythm. 8 9
• Jet lag and behavioral alternatives: Melatonin may help with sleep onset in a new location, but light, temperature, and exercise can be used to shift the body clock. 10