Horripilation: What is it?

Explore what is horripilation and how it happens

Have you ever felt the hair on your arms stand up on a chilly evening or felt shivers run down your spine while watching a scary movie? The colloquial name for this phenomenon is goosebumps. In scientific parlance, this is horripilation.

Characterised by small bumps that develop on a person’s skin, underneath the hair follicles, horripilation is an involuntary reaction to cold weather. It has also been recorded in animals, such as when a cat raises its hackles. It is controlled by the sympathetic nervous system. Specifically, horripilation happens when the brain sends signals to tiny muscles called arrector pili in hair follicles causing them to contract. This is what makes the hair stand upright.

The most common cause of horripilation is cold air near the skin. But researchers have also documented intense emotions, such as fear, shock, anxiety, love, sexual desire and inspiration, as also having the same effect.

In most cases, horripilation is temporary. But if it persists, it could be a sign of a medical condition, like keratosis pilaris. Its symptoms include lumps that feel rough and dry and mimic goosebumps. These lumps are dead skin cells; they appear on the cheeks, bottom and front of the thighs, and the upper arms. They go away on their own or can be made to with the help of dermatological creams.