Scientists Say: Melatonin | Science News for Students

Scientists Say: Melatonin

This hormone helps control when we sleep
Jun 25, 2018 — 6:30 am EST
girl sleeping

Melatonin is a hormone that helps to control when we sleep and wake up.


Melatonin (noun, “Mell-ah-TOH-nin”)

This one is a real snooze. Melatonin is a hormone — a chemical that is produced in one area of the body that travels through the blood. This hormone is produced in the brain in the pineal gland, which is tucked in a groove just behind the very center of the brain.

Melatonin regulates the body’s circadian rhythm, or how the body functions on a 24-hour cycle. Levels of melatonin in the blood peak at night, during sleep, and drop in the morning when a person wakes up.

Light helps control when melatonin levels rise and fall. When a person is exposed to only external light, their melatonin levels follow a natural pattern. But that pattern can be disrupted by exposure to manmade light sources, such as a smartphone. That can make it more difficult to sleep or wake up on time. Moving from one time zone to another can also disrupt a person’s bodily rhythms. Some people take extra melatonin, in the form of a pill, at night to help them adjust.

In a sentence

The blue light from electronic devices can prompt a person’s body to produce less melatonin, which can sabotage their sleep.

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Power Words

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circadian rhythm     Biological functions such as body temperature and sleeping/waking times that operate on a roughly 24-hour cycle.

disrupt     (n. disruption) To break apart something; interrupt the normal operation of something; or to throw the normal organization (or order) of something into disorder.



melatonin     A hormone secreted in the evening by a structure in the brain. Melatonin tells the body that it is nearing time to sleep. It plays a key role in regulating circadian rhythms.

pineal gland  A tiny area of the brain located deep in the center, right behind the thalamus. The pineal gland is shaped a bit like a pinecone, which is where it gets its name. It releases the hormone melatonin, which helps control when we sleep and wake up.