Key Takeaways
- The fight-or-flight response is your body’s natural reaction to danger.
- It triggers physical and psychological changes that prepare your body to deal with the threat.
- Learn how to calm your body after this response can help you manage anxiety and improve overall well-being.
The fight-or-flight response is your body’s natural, automatic reaction to stress or danger. It triggers physiological changes, such as a faster heart rate and tenser muscles, that prepare your body to deal with the source of the stress. This can be helpful in the short term, but if it goes on too long without giving your body a chance to relax, it can have negative effects on your physical and mental health.
Illustration by Joshua Seong. © Verywell, 2018.
How the Fight-or-Flight Response Works
The fight-or-flight response, also known as the acute stress response, refers to the physiological reaction that occurs when in the presence of something mentally or physically frightening or stressful. This response is triggered by the release of hormones that prepare your body to either stay and deal with a threat or run away to safety.
The three stages of fight-or-flight are:
- The alarm stage: During this stage, the central nervous system is ramped up, preparing your body to fight or flee.
- The resistance stage: This is the stage in which the body attempts to normalize and recover from the initial elevated fight-or-flight response.
- The exhaustion stage: If the first two stages occur repeatedly over time, such as when under chronic stress, the body can feel exhausted and begin to break down.
Physiologic Changes
The sudden release of hormones activates the body’s sympathetic nervous system in response to acute stress. Fight-or-flight response hormones include adrenocorticotropic and corticotropin-releasing hormones.
These hormones cause the sympathetic nervous system to stimulate the pituitary and adrenal glands, triggering the release of catecholamines, including adrenaline, noradrenaline, and cortisol.
This chain of reactions results in various reactions, including increased:
- Heart rate
- Blood pressure
- Breathing rate
Your body can stay in fight-or-flight for minutes to hours after the threat is gone, which is how long it takes for the parasympathetic nervous system to return to pre-arousal levels.
Why Do We Have It?
The term “fight-or-flight” represents the choices our ancient ancestors had when faced with danger in their environment: to either fight or flee. In either case, the physiological and psychological response to stress prepares the body to react to the danger.
In the 1920s, American physiologist Walter Cannon was the first to describe the fight-or-flight response. Cannon realized that a chain of rapidly occurring reactions inside the body helped to mobilize the body’s resources to deal with threatening circumstances.
Today, the fight-or-flight response is recognized as part of the first stage of Hans Selye’s general adaptation syndrome, a theory describing the stress response.
How to Tell If You’re Having a Fight-or-Flight Response
Physical signs that can indicate that your fight-or-flight response has kicked in include:
- Dilated pupils: In times of danger, the body prepares itself to become more aware of its surroundings. Dilation of the pupils allows more light into the eyes, resulting in better vision of your surrounding area.
- Pale or flushed skin: During fight-or-flight, blood flow to the surface areas of the body is reduced, while flow to the muscles, brain, legs, and arms is increased. Paleness or alternating between a pale and flushed face as blood rushes to the head and brain is common. The body’s blood clotting ability also increases to prevent excess blood loss in the event of injury.
- Rapid heart rate and breathing: Heartbeat and respiration rate increase to provide the body with the energy and oxygen needed to fuel a rapid response to danger.
- Trembling: The muscles tense and become primed for action, which can cause trembling or shaking.
You can probably think of a time when you experienced the fight-or-flight response. When faced with something frightening, you can feel your heartbeat quicken, you may start breathing faster, and your entire body becomes tense and ready to take action.
Why It Can Be Helpful
The fight-or-flight response plays a critical role in dealing with stress and danger in our environment. When we are under threat, the response prepares the body to either fight or flee. By priming your body for action, you are better prepared to perform under pressure.
The stress created by the situation can actually be helpful, making it more likely that you will cope effectively with the threat.
- Better performance: This type of stress can help you perform better in situations where you are under pressure to do well, such as at work or school.
- Inspires prosocial actions: Some experts suggest that the fight-or-flight response may even benefit when the urge to fight others in an attempt to harm them is transformed into the urge to fight to protect them. This may be beneficial when the fight-or-flight response is triggered by negative emotions such as anger and fear.
- Improves chances of survival: In life-threatening situations, the fight-or-flight response plays a critical role in survival. By gearing you up to fight or flee, it makes you more likely to survive the danger.
When It Becomes Harmful
While the fight-or-flight response happens automatically, that doesn’t mean that it is always accurate. Sometimes we respond in this way even when there is no real threat.
This is because the fight-or-flight response can be triggered by both real and imaginary threats. Phobias are good examples of how the fight-or-flight response might be falsely triggered in the face of a perceived threat.
Constantly being in a state of fight-or-flight, such as when facing repeated stressors, can also be harmful to your health. Chronic stress can increase your risk of:
Is Anxiety a Fight-or-Flight Response?
Some research indicates that the body’s desire to fight or flee can increase a person’s risk of developing an anxiety disorder, making them more vulnerable to this type of mental health condition.
Common Examples
The fight-or-flight response can happen in the face of imminent physical danger, such as when encountering a growling dog during your morning jog. It can also be the result of a psychological threat, such as preparing to give a big presentation at school or work.
Another example of the fight-or-flight response is if a person who is terrified of heights has to go to the top floor of a skyscraper to attend a meeting. Their body might go on high alert, with their heartbeat and respiration rate increasing. If the response is severe, it can lead to a panic attack.
How to Calm Down After Fight or Flight Kicks In
Understanding the body’s natural fight-or-flight response is one way to help cope with such situations. When you notice that you are becoming tense, you can start looking for ways to calm down and relax your body.
Ways to calm the fight-or-flight response include:
The stress response is one of the major topics studied in the rapidly growing field of health psychology. Health psychologists are interested in helping people find ways to combat stress and live healthier, more productive lives.
By learning more about the fight-or-flight response, psychologists can help people explore new ways to deal with their natural reactions to stress.
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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