Melatonin

Melatonin signals the timing of night and sleep, but supplements appear to offer limited sleep benefits and may affect hormones, so caution is warranted.

1. Sleep onset, not sleep quality: Melatonin helps signal when it is time to sleep, but does not ensure sleep quality or structure. In healthy adults who are not older, a meta-analysis found average increases of just 3.9 minutes of sleep and 2.2% in sleep efficiency. 1

2. Limit light during the night: Bright light can sharply suppress melatonin. If you need light in the middle of the night, use as little as needed; dim red or amber light is less likely to suppress melatonin than bright light. 2

3. Hormone effects and children: Melatonin can inhibit hormones involved in puberty; commercial supplements may contain substantially different amounts than their labels state. Melatonin also affects bone mass and gonad maturation. 3 4

4. Potential use and alternatives: Melatonin may be considered for jet lag or older adults, for whom pineal-gland calcification may contribute to sleep difficulties. For shifting the body clock, behavioral approaches—including timed light exposure, exercise, and temperature—are alternatives. 5 6