Fight or Flight Response

Stress and anxiety are felt when the body reacts as though it is in danger. This is a natural reaction designed to help us to react quickly to danger – to ‘fight, flee or freeze’. However, it can be triggered when there is no actual danger. This stress response is sometimes called ‘fight or flight.’

The following animation explains what happens during the ‘fight or flight response.’ Watch the animation or continue to read about it below.

Many things happen in the body during the fight or flight response. These are caused by our central nervous system telling our body to get ready to fight or to get away from danger.

There are noticeable effects:

  • Dilated pupils
  • Dry mouth
  • Tense muscles
  • Fast heart beat
  • Chest pains
  • Palpitations
  • Sweating
  • Fast and shallow breathing/hyperventilation

There are also hidden effects:

  • The brain is getting the body ready for action
  • Adrenaline is released
  • Blood pressure rises
  • The liver releases glucose to provide energy for muscles
  • Digestion slows or stops
  • Sphincter muscles close then relax
  • Cortisol is released (this depresses the immune system)

Most of the symptoms of stress, anxiety, and fear can be explained by the fight or flight response. For example:

Bodily reactionReason for this reactionWhat you experience
Your brain struggles to think logically.When you’re in danger, you don’t need to think, you just need to react.You can’t think straight. You tend to act first and think later.
Your brain tunes in to notice any potential danger around you.You need to spot danger to survive a dangerous situation.You tend to notice things that add to stress. It is hard to notice signs that everything is OK and you become more anxious.
Your heart beats faster and the small blood vessels dilate.Your heart pumps blood around the body to your lungs and large muscles so that you are ready to run away.Your heart is pounding. You might feel lightheaded and sweaty.
Your digestive system slows down and your bowels relax.You have no need to digest food when you’re under attack. You need to empty your bowels so that you can escape quickly.You feel butterflies in your stomach and you don’t feel hungry. Instead, you need to go to the toilet.

All of these ‘fight or flight’ symptoms are normal and helpful in dangerous situations. However, they can make you feel unwell if they are experienced every day. They can also make it hard for you to think logically or rationally. If you have been, or are, very stressed, angry or worried, then you will need time to calm down before you can think ‘straight’ again. Relaxation exercises can help you to do this.