Skip to the answer

Why do we shiver?

The short answer

Shivering is your body turning on its own heater. Your brain tells your muscles to squeeze and relax very fast, and that work comes out as heat.

Fact-checked Checked against 9 sources

Watch it in about a minute, here or on YouTube

When you get cold, your body starts to shake all by itself. That shaking is your body turning on its own heater.

Who starts the shaking?

Deep in your brain, the hypothalamus works like a thermostat. When it senses you are too cold, it tells your muscles to shiver.

Illustration from the video: Who starts the shaking?

How does shaking warm you?

Your muscles squeeze and relax again and again very fast. Every squeeze uses energy, and that energy comes out as heat. Even your teeth chatter, because your jaw muscles shiver, too.

Illustration from the video: How does shaking warm you?

Illustration from the video: How does shaking warm you?

Why shiver with a fever?

The same thermostat is why you can shiver when you have a fever. To fight germs, your brain turns the thermostat up, so you feel cold even when you are not. Your muscles shiver until your body warms up to the new setting.

Illustration from the video: Why shiver with a fever?

Sources

Keep asking

See all 54 answers