What Is the Fight or Flight Response? Causes, Symptoms and How to Calm It

Originally Published 14 June 2015 | Updated 26 July 2026

The fight or flight response is the body’s automatic survival response. It prepares you to deal with situations your brain believes may threaten your safety by increasing alertness and making physical changes that support rapid action. Although this response evolved to help our ancestors survive immediate danger, it can also activate during modern experiences such as anxiety, phobias, public speaking or flying. Understanding how the fight or flight response works can help explain why these reactions happen and what you can do to reduce unnecessary activation.

 

 

The fight or flight response is one of the body’s natural survival systems, yet many people don’t understand what it is or why it happens. I explain it because it helps people make sense of experiences that can otherwise feel confusing. Whether someone is dealing with anxiety, panic, a specific fear, or another situation where their body suddenly feels on high alert, understanding this response gives them a clearer picture of what their nervous system is doing. Once you know why your body reacts in this way, many symptoms begin to make much more sense.

 

 

 

What is the fight or flight response?

The fight or flight response is an automatic survival response that helps us deal with situations our brain believes could threaten our safety. It happens long before we have consciously decided whether we are in danger.

When the brain detects a possible threat, the hypothalamus activates the sympathetic nervous system. Within seconds, the adrenal glands release adrenaline and noradrenaline, increasing heart rate, breathing and blood flow to the muscles. At the same time, another stress pathway known as the hypothalamic-pituitary-adrenal (HPA) axis begins releasing cortisol, helping the body stay alert until the situation has passed.

The purpose is to prepare the body for action. From an evolutionary perspective, they increase the chances of surviving dangers that require a rapid physical response.

Although this system evolved to deal with immediate threats, it does not only respond to physical danger. The brain constantly interprets information from both the outside world and inside the body, estimating whether a situation could affect our safety or wellbeing. If it judges that a threat exists, it activates the same survival response, regardless of whether the danger comes from a predator, a public speaking event, turbulence during a flight or another situation that feels unsafe.

This explains why someone with a fear or phobia can experience a racing heart, tense muscles or rapid breathing even when they know they are not in immediate physical danger. The body responds to the brain’s prediction, rather than to objective reality. Understanding this process often helps people recognise that these physical sensations are signs of a working survival system, rather than evidence that something has gone wrong.

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How can hypnosis help?

When the fight or flight response activates frequently, you spend more time in a state of heightened alert. Some people notice that they feel constantly on edge, struggle to relax or find that everyday situations trigger the same survival response that once evolved to deal with immediate danger.

Hypnosis provides an opportunity to work with these learned patterns. During hypnosis, people experience a state of focused attention and deep relaxation, making it easier to explore unhelpful associations, reduce unnecessary threat responses, and develop new ways of responding to situations that previously triggered anxiety or fear.

I see hypnosis as one part of a wider approach. The nervous system responds to the way we live, not only to the thoughts we have. Sleep, movement, social connection, time in nature and other everyday experiences all influence how safe the body feels. As these needs receive more attention, many people find that their fight or flight response becomes less sensitive, because the brain no longer needs to remain on such a high level of alert.

Understanding why the body responds in this way can help you have a sense of clarity. From there, hypnosis can help reinforce new patterns that support a calmer, more flexible response to life’s challenges.

 

 

 

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