We humans don’t come with an instruction manual. If we did, I suspect we’d do a better job of getting through life with less pain and more joy.

Human behavior has evolved over time. What worked for us humans a few thousand years ago may not be as helpful today. So while our behavior adapts to the changing times and environment, it’s thought that it never completely forgets its evolutionary roots.

One of the driving forces of some human behavior is something called the “fight or flight response” (also known as the acute stress response). This is the psychology term that describes one of the ways we can react when under stress.

Understanding the purpose of the fight or flight response can lead to greater insights into our own behavior when we’re stressed out.

The fight or flight response is characterized by feeling bodily sensations of stress — for instance, an increased heart rate and faster breathing. You can feel a pressure in your chest as though something is pressing down on you. You may also have heightened sensory sensitivity — you’re more sensitive to sights or sounds around you.

All of this occurs to ready the body for one of two reactions to a perceived threat in our environment — to fight or to run (flight).

The body’s sympathetic nervous system is the thing responsible for readying the body for one of these reactions. It stimulates the adrenal glands, which in turn trigger the release of things like adrenaline and noradrenaline. This is what causes the body to increase its heart rate, blood pressure and breathing rate.

When the threat has been removed — either by running away from it, or by defeating it through fighting — it can take up to an hour for the body’s sympathetic nervous system to return to its normal level.

The evolutionary purpose of this response is obvious. In prehistoric times, a person might have found themselves in a situation where a quick choice has to be made. If the person had spent a lot of time thinking about it, they may have become dinner for a lion or other animal. The body’s fight or flight response, it’s theorized, took thinking out of the equation so we could react more quickly — and stay alive.

As our bodies and minds have adapted and evolved to the changing times, the threats have become less obvious — and sometimes they aren’t even real. Today, our body can react to even perceived or imagined threats.

Virtually any phobia can trigger the fight or flight response. People afraid of heights, for instance, will not only feel an overwhelming fear of them — they will feel their body react to being in a high place through increased heart and respiration rates. Standing up in front of a crowd to give a presentation can do the same for some people — triggering the fight or flight response even though there is no real threat.

Recognizing your body’s response to an immediate stressor or threat can help you react accordingly. Through relaxation and meditation exercises, you can actually tell your body, “Hey, this isn’t a real threat, let’s calm down.”

For Additional Reading…