Picture this: You’re sitting on your couch in the dark alone, watching a scary movie. The killer is walking toward an unsuspecting victim, then suddenly jumps out at her. In that moment, the hairs on your body stand up, and you get a shiver down your spine. When you go for a walk on a crisp morning, the same thing happens. When the music swells during your favorite song, you get the shivers again, this time with the little goosebumps on your arms that appear when you get that sensation.
There’s a good reason for shivers and goosebumps: they’re your body’s response to emotion or stress. We got this from our animal ancestors. When they were cold, the hair on their bodies would stand up—the movement of the arrector pili muscle would cause the skin to contract, raising each hair—to provide an extra layer of insulation. This response is also in play when animals feel threatened: their natural reaction is to try to look bigger than their attacker, so their skin and hair expand to play up that effect. The part of the brain called the hypothalamus is what controls this reaction.
So why do goosebumps—also known as cutis anserina or piloerection—appear, aside from the functional purpose of looking larger or creating insulation? It’s because our emotions are also connected with the hypothalamus, so sometimes goosebumps are just our body reacting to our brain’s signals of intense emotion.
When we feel things like love, fear, or sadness, the hypothalamus sends a signal to our bodies that produce adrenaline in our blood. The signal triggers the arrector pili muscles to contract, and then we have goosebumps caused by emotion. The sudden adrenaline rush may also cause sweaty palms, tears, increased blood pressure, or shivers.
When we listen to music and get shivers, it is a mixture of subjective emotions toward the music and physiological arousal. If we hear a song we get excited about, or a song that makes us sad, the hypothalamus reacts to the sudden change in emotion and we physically feel the shiver along our spine.