Why do we shiver?
We shiver to warm up. Shivering is an automatic response in which muscles rapidly tighten and relax, producing heat to raise body temperature when we are cold.
The hypothalamus, a region of the brain, acts like a thermostat, keeping body temperature around 37 degrees Celsius. When it detects that the body is getting too cold, it signals muscles to contract quickly and involuntarily. These small, rapid movements burn energy and release heat, which can increase heat production several times.
Shivering is often accompanied by goosebumps, when tiny muscles make hairs stand up, and by narrowing of blood vessels in the skin to reduce heat loss. People also shiver at the start of a fever, when the brain raises the body's target temperature to fight infection.
When shivering stops
If the body becomes dangerously cold, a condition called hypothermia, shivering can actually stop, which is a serious warning sign. Severe hypothermia needs emergency medical help. Fear, anxiety and strong emotions can also cause trembling similar to shivering.
Did You Know?
Babies cannot shiver well. Instead, they warm themselves using a special type of fat called brown fat.
This answer is general information, not medical advice. For a personal health question, talk to a doctor.