Why Do We Get Goosebumps?

KohakuHave you ever wondered about that tingly, bumpy feeling on your skin when it's cold or when something moves you?

The answer in 30 seconds

Goosebumps happen when tiny muscles at the base of each hair contract. In animals, raising hair helped keep warm or look bigger to scare off threats.

Goosebumps are caused by tiny muscles at the base of each hair. Cold, fear, excitement, and other strong feelings make these muscles contract automatically, which raises the hair and creates small bumps on the skin. In furry animals this helps keep warm or look bigger, but in humans it has little use.

Tiny Muscles at the Base of Hairs

Goosebumps happen when tiny muscles attached to each hair—called arrector pili—contract. This makes the hair stand up straight and the skin around it form a small bump. It is an automatic reaction controlled by the sympathetic nervous system, the part involved in fight-or-flight responses—not something we do on purpose.

Figure: How goosebumps happen

What Happens When It’s Cold

When we are cold, standing hair creates a layer of air between hairs, which helps animals with thick fur keep body heat. For furry animals, raised hair acts like insulation. In humans, body hair is thin, so goosebumps keep little heat, but the reaction remains.

KohakuHumans have thin body hair, so we don't keep much heat this way—but the reaction still lingers as a little reminder of our animal past.

Strong Emotions and Adrenaline

Goosebumps also appear with strong emotions such as fear, surprise, awe, or excitement. The adrenal glands release a hormone called adrenaline, which makes the tiny hair muscles contract. In animals, raised hair makes them look bigger and can scare off threats—think of a cat arching its back and puffing up. In people, goosebumps can happen at weddings, award ceremonies, or while watching a scary movie.

Not the Same as Chills

Goosebumps are not the same as chills. Chills are shivering caused by rapid muscle contraction and relaxation that helps produce heat, often before a fever. Goosebumps are hair standing up from cold air or strong emotions. You can have chills with or without goosebumps. Goosebumps themselves are usually harmless.

Want to know more?

The medical term for goosebumps is piloerection. They can appear anywhere you have hair, such as your neck, arms, or legs.
A recent study found that the nerves that make these tiny muscles contract are the same nerves that stimulate hair follicle stem cells, which may explain why cold weather can also make an animal's fur grow thicker.
Goosebumps can also appear with frisson—shivers and goosebumps linked to music, films, speeches, or ASMR.

KohakuGoosebumps are a small signal from your body in response to cold or strong feelings. Most of the time, they're nothing to worry about.

Quick quiz: test yourself

What happens under the skin when you get goosebumps?

Show the answer

Tiny muscles at the base of hairs contract, making hairs stand up
Sweat glands release a lot of sweat
Blood vessels widen to release heat

Tiny muscles at the base of hairs contract, making hairs stand up Goosebumps are caused by tiny muscles at the base of hairs contracting, which makes the hairs stand up and the surrounding skin rise.

Sources

Why do humans get "goosebumps" when they are cold, or under other circumstances?Scientific American
Chills: MedlinePlus Medical EncyclopediaMedlinePlus（米国国立医学図書館）
Goosebumps: What They Are and Why They HappenCleveland Clinic

This article was written after checking the sources above as of 2026-10-03. Explanations may change as research progresses. Photo credits are shown below each photo.