Melatonin is a hormone that signals to the brain and body when it's day and when it's night, aiding the timing of the onset of sleep, but not necessarily aiding in the generation of sleep itself. Melatonin is released in the evening and helps to signal that it's time to sleep for diurnal species like humans. While it helps transition to sleep, it does not ensure the overall structure of sleep throughout the night. Melatonin supplementation in healthy adults is not particularly helpful for improving sleep, with studies showing minimal increases in total sleep time and efficiency 1.

Regarding light exposure, it should be minimized in the middle of the night to prevent disruption of melatonin production. Long wavelength light, like red or amber, is less likely to inhibit melatonin than bright light 2.

Melatonin has a significant impact on hormones and puberty, especially in children, where it can inhibit hormones such as GnRH, LH, testosterone, or estrogen during growth. Melatonin supplements can contain inconsistent dosages, potentially affecting the hormone system and other bodily functions 3. It's also crucial to consider that melatonin regulates other bodily processes, including bone mass and gonad maturation 4.

Melatonin and Sleep

Matt and Andrew discuss the role of melatonin in regulating sleep and whether or not melatonin supplements are effective for improving sleep. While melatonin helps with the timing of sleep, it doesn't necessarily aid in the generation of sleep itself. Studies suggest that melatonin supplementation is not particularly helpful for healthy adults and only increases total sleep time by an average of 3.9 minutes and sleep efficiency by 2.2%.

Huberman Lab

Dr. Matthew Walker: The Science & Practice of Perfecting Your Sleep | Huberman Lab Podcast #31

Therefore, while melatonin can be useful for adjusting to jet lag and for older adults with calcification of the pineal gland, advises caution with its supplementation due to dosage inconsistencies and its broader impact on the hormone system 5. It’s generally recommended to resort to behavioral methods like light exposure and temperature regulation to manage sleep and circadian rhythms 3.