This Is Your Body on Fear

Right as Rain Fact Checked
A woman sits alone in a car at night.
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Do you ever wonder why your heart races and you can’t think clearly when you’re afraid? Sure, you may not actually need to fear that skeleton in the haunted house or zombie streaming through the screen, but try telling that to your body’s fear response. 

When you’re scared, even if it’s just from good old-fashioned Halloween fun or your favorite TV show, your brain sets off an elaborate and coordinated set of responses to help you stay safe. Physical changes — from deep inside your brain all the way to the muscles in your legs — happen in seconds. 

Fear starts in the brain 

“Our body and brain are hardwired to experience fear. It keeps us safe and helps us avoid potential calamity,” says Dr. Jennifer Erickson, a psychiatrist at UW Medical Center and UW Medicine Primary Care.  

Most of us don’t have to think about breathing, digesting our food or making our heart beat. The autonomic nervous system takes care of these functions we think of as automatic. It is divided into two branches: the parasympathetic nervous system (the rest and digest system) and the sympathetic nervous system (the fight-or-flight system).  

Fear kicks your fight-or-flight response into overdrive. Your adrenal glands secrete adrenaline. Functioning decreases to your brain’s frontal lobe, which is responsible for logical thinking and planning, and the deeper, more animalistic parts of your brain — including the amygdala — take over. You may notice your thoughts racing or that you can’t focus on things unrelated to the perceived threat. 

You may get sweaty and flushed or have cold, clammy hands when you’re afraid. That’s because the blood flows away from the edges of the body toward the larger, interior muscles. 

You’ll also experience a decrease in digestive activity. Peristalsis, which is a wave-like movement in the gastrointestinal system that controls digestion, takes quite a bit of energy that your body does not have time for when you’re trying to avoid joining the undead ranks. 

“These processes happen automatically and very quickly, where things we might not typically interpret as dangerous might be automatically interpreted as a threat,” says Beth Lehinger, a postdoctoral research fellow in the Department of Psychiatry and Behavioral Sciences at the UW School of Medicine. 

That’s why you may startle if you catch your reflection out of the corner of your eye in a dark hallway — your brain is reacting to a possible threat seconds before you become aware there is no threat.

It may be called the fight or flight response, but there’s a third thing that can happen: freezing. 

“People who freeze seem to have either a history of trauma and lots of experience with things they had no control over, or they have no experience with things like that,” Erickson explains. 

Try not to get down on yourself for whatever your fear response manifests as. Your body is doing what it thinks it needs to do in the moment to keep you safe. 

Anxiety is fear out of context 

The fear response is designed to deal with imminent physical dangers. But we live in a society and at a time when we aren’t regularly running from lions, tigers and bears. Instead, the kind of danger we experience is more psychological or social in nature.  

But your brain — which tends to overgeneralize — can’t tell the difference, says Kari Stephens, a clinical psychologist at the UW School of Medicine who sees patients at UW Medicine Primary Care at Northgate. That means your brain can react to something like missing a work deadline the same way it would respond to something that’s actually life-threatening, like a car crash or an earthquake. 

Some of this anxiety can actually be good. It protects you by telling you when there is something coming your way that you need to deal with. Helpful anxiety activates you and helps you remember to do important things, like going grocery shopping or being on time for your doctor’s appointment.  

For people who have an anxiety disorder, the response crosses a line where it’s no longer healthy, but is interfering with life, says Stephens. Say that work deadline isn’t for two weeks, but you’re so worried you won’t get the project done that you can’t get anything else done. Or you get so nervous about going out at night that you miss out on social gatherings. That’s when it’s no longer “good” anxiety. 

Anxiety can manifest in different ways, all of which involve fear about the future — and any type of anxiety can be accompanied by any of the body responses that the fear response causes, says Lehinger.   

“People with anxiety will describe that they feel exhausted at the end of the day because they’re regularly in that fight or flight response,” says Erickson.  

Sometimes people will be scared by how their body responds to fear — a fear of fear, if you will — that sends them into a spiral. They avoid non-dangerous things that provoke fear because they don’t want to feel all the uncomfortable physical sensations that come with fear, Lehinger says. But that only makes fear grow — it’s better to tackle fear and anxiety through things like therapy or medication, or both, than letting fear run your life.  

“Fear gets people through some really difficult situations. But once you’re out of them it’s OK to learn to live without that level of fear,” Erickson says. 

This article was originally published on October 25, 2017. It has been reviewed and updated with new info. Kristen Domonell and McKenna Princing contributed to this article.