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

(more about Power Words)

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

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.

gland     A cell, a group of cells or an organ that produces and discharges a substance (or “secretion”) for use elsewhere in the body or in a body cavity, or for elimination from the body.

hormone     (in zoology and medicine) A chemical produced in a gland and then carried in the bloodstream to another part of the body. Hormones control many important body activities, such as growth. Hormones act by triggering or regulating chemical reactions in the body. (in botany) A chemical that serves as a signaling compound that tells cells of a plant when and how to develop, or when to grow old and die.

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.