The Link Between PTSD and Fight or Flight Response

scared woman walking down street at night
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Everyone is going to encounter some kind of stressful or dangerous situation in their lifetime, and fortunately, our body has a natural, built-in stress response to threatening situations called the "fight or flight response."

Learning about our body's natural response to threat and danger can help us better understand the symptoms of post-traumatic stress disorder (PTSD).

The Difference Between Anxiety and Fear

Before we discuss what happens in the fight or flight syndrome, it is important to first discuss the difference between fear and anxiety.

Fear is the emotion you experience when you are actually in a dangerous situation. Anxiety is what you experience leading up to a dangerous, stressful, or threatening situation. You may also experience anxiety when you think about something stressful or dangerous that could happen to you. Other words for anxiety may be "dread" or "apprehensiveness."

The difference between anxiety and fear can be illustrated nicely this way. Think about the last time you went on a roller coaster. Anxiety is what you felt when you were in line looking at the hills, steep drops, and loops, as well as hearing the screams of other riders. You also likely felt anxiety when on the roller coaster as you got closer to the top of the first hill. Fear is what you experienced as you went over the peak of the hill and started your fall down the first hill.

Anxiety and Fear Are Adaptive, Automatic Responses

You may be surprised to learn that anxiety and fear are often helpful emotions. In fact, the human race may not even exist if it were not for these hard-wired responses to danger and threat. Anxiety and fear provide us with information. That is, they tell us when danger is present, and they prepare us to act.

When you are in a stressful or dangerous situation and experience fear and anxiety, your body goes through a number of changes:

  • Your heart rate may increase.
  • Your vision may narrow (sometimes called "tunnel vision").
  • You may notice that your muscles become tense.
  • You may begin to sweat.
  • Your hearing may become more sensitive.

All of these changes are part of the fight or flight response. As the name implies, these changes are preparing you for immediate action. They are preparing you to flee, freeze (kind of like a deer does when caught in someone's headlights), or to fight.

All of these are adaptive bodily responses essentially designed to keep us alive, and because these responses are important to our survival, they occur quickly and without thought. They are automatic.

The Downside

It would be great if anxiety and fear only occurred in situations where we were in immediate danger. Unfortunately, it does not always work this way. For example, many people have fear and anxiety when speaking in front of other people. You may also have fear and anxiety when meeting someone new. A person with PTSD may experience fear and anxiety when they go out into crowded or cramped places, such as a grocery store or a subway. These situations are not dangerous in the sense that they don't threaten our survival. So, why might we have fear and anxiety in these situations?

We have fear and anxiety in these situations because of the way we evaluate these situations. Our body cannot always tell the difference between real and imagined threats. Therefore, when we interpret a situation as threatening, our body is going to respond as though that situation is dangerous and threatening, even if it really isn't in actuality.

The Fight or Flight Response and PTSD

When people experience something traumatic and/or have PTSD, they may no longer feel as though the world is a safe place. It may feel as though danger is everywhere. As a result, a person may constantly be in a state of fear and anxiety.

For this reason, cognitive-behavioral treatments for PTSD often focus a lot of attention on altering the ways in which people interpret their environment. Mindfulness may be another way of "taking a step back" from thoughts, reducing their power to activate the fight or flight response.

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  • Fishman J. (2013). What are some of the physiological manifestations of PTSD? Psych Central.
  • Sherin JE. Post-traumatic stress disorder: the neurobiological impact of psychological trauma. Dialogues Clin Neurosci. 2011 Sep;13(3):263-78.

By Matthew Tull, PhD
Matthew Tull, PhD is a professor of psychology at the University of Toledo, specializing in post-traumatic stress disorder.