serotonin

American  

[ser-uh-toh-nin, seer-] / ˌsɛr əˈtoʊ nɪn, ˌsɪər- /

noun

Biochemistry.

1. a neurotransmitter, derived from tryptophan, that is involved in sleep, depression, memory, and other neurological processes.

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serotonin British  

/ ˌsɛrəˈtəʊnɪn /

noun

1. a compound that occurs in the brain, intestines, and blood platelets and acts as a neurotransmitter, as well as inducing vasoconstriction and contraction of smooth muscle; 5-hydroxytryptamine (5HT)

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serotonin Scientific  

/ sĕr′ə-tō′nĭn,sîr′- /

1. A monoamine substance that is formed from tryptophan and found in many animal tissues, including the intestine and central nervous system. In the brain, serotonin acts as a neurotransmitter that is involved in the control of pain perception, the sleep-wake cycle, and mood. Serotonin is also produced in some bacteria and plants.

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Etymology

Origin of serotonin

First recorded in 1945–50; sero- + tone + -in ²

Compare meaning

How does serotonin compare to similar and commonly confused words? Explore the most common comparisons:

• dopamine vs. serotonin

Explanation

Serotonin is a chemical in the human body known as the “feel-good chemical.” It helps regulate things like mood, sleep, and appetite. Some of it is in your brain but most of it is in your gut. Serotonin helps cells talk to each other. As serotonin has been studied by scientists over the years, it's become clear how important it is for helping people avoid depression and anxiety. With enough serotonin in your brain, you're able to sleep soundly, learn new things, and remember things clearly. Serotonin also helps with digestion, blood clotting, and bone density. Doctors first discovered serotonin in the 1940s.

Example Sentences

The medications discussed in the study include selective serotonin reuptake inhibitors, commonly known as SSRIs.

From Science Daily • May 15, 2026

Scientists have uncovered new evidence that serotonin, a brain chemical best known for helping regulate mood, may also worsen tinnitus, the persistent ringing or buzzing sound that affects millions of people worldwide.

From Science Daily • May 15, 2026

These antidepressants are widely prescribed for moderate to severe depression and anxiety because they raise serotonin levels in the brain.

From Science Daily • May 15, 2026

Amir Khan, a doctor, broadcaster and president of the RSPB, said: "Hearing birdsong, especially during the dawn chorus when they're at their loudest and most beautiful, can produce more serotonin and make us feel good."

From BBC • May 9, 2026

I recalled from my music research that enjoyable music stimulates the production of the hormone serotonin, which makes us feel joy and elevates our moods by altering our brain waves.

From "Sir Fig Newton and the Science of Persistence" by Sonja Thomas