A slight touch, an emotional moment, or a particularly cold day can all give us goosebumps. Everyone experiences goosebumps from time to time. When it happens, the hairs on your arms, legs, or torso stand up straight. The hairs also pull up a little bump of skin, the hair follicle, up with them.
The medical terms for goosebumps are piloerection, cutis anserina, and horripilation. The term “goosebumps” is most widely used because it’s easy to remember: The little bumps that form on your skin when this phenomenon happens look like the skin of a plucked bird.
When It's Chilly
Your body works hard to maintain a relatively constant temperature. In cool conditions, activation of nerves from the sympathetic branch of the involuntary nervous system cause constriction of blood vessels in the skin, which conserves body heat. Sympathetic nerve stimulation of the skin also frequently triggers the pilomotor reflex. In furry mammals, this reflex also helps conserve heat by trapping warm air around the skin surface. However, the reflex is not an effective heat-conservation mechanism in people since humans lack dense body hair. Thus, the pilomotor reflex is a rudimentary nervous system remnant from humans' animal ancestors.
An area of your brain called the hypothalamus regulates your target body temperature, much like the thermostat in your home. Fever occurs when the hypothalamus increases your body's target temperature to an above-normal level. This triggers responses akin to what occurs in cool environmental temperatures, including stimulation of sympathetic nerves to your skin. Thus, goosebumps can occur if you have a fever -- along with chills and shivering.
Are You Scared?
Among other functions, the sympathetic nervous system stimulates your fight-or-flight response. This is the almost instantaneous, adrenaline-driven reaction that kicks in whenever you encounter a dangerous or scary situation. Thus, fear is frequently accompanied by goose bumps -- the derivation of the idiom, making your hair stand up. In some instances, the perceived threat might not be real or physically imminent. So you might get goose bumps while watching a scary movie, reading a horror fiction novel, or even pondering a terrifying thought.
Riding Emotional Waves
Strong, intense emotions often trigger a wave of goosebumps. Sexual arousal also brings on goose bumps in some people. Again, the origin is believed to be involuntary electrical signaling from the sympathetic nervous system. Almost any strong emotion can potentially stimulate the pilomotor reflex, including love, joy, admiration, anger, disgust and sadness. Goose bumps typically occur in the moment, but can also develop when recalling emotional memories. The development of goose bumps while listening to music or even thinking of certain songs is thought to relate to the music provoking intense feelings or emotional memories.
In most cases, goosebumps are nothing more than a temporary nuisance. However, goosebumps can be a sign of a long-lasting or serious medical condition. For example, goosebumps can also be a sign of:
Keratosis pilaris. A harmless and common skin condition that creates the look of goosebumps on the skin for long periods of time.
Autonomic dysreflexia. An overreaction of the nervous system caused by a spinal cord injury.
Temporal lobe epilepsy. A chronic seizure disorder.
Chills. For example, those associated with fevers caused by influenza.