The Fight or Flight Response

What is the most common scenario if we perceive serious danger? We either run away or, if that is not possible, fight back.  Whichever happens, a whole range of biological actions are instantly triggered in our body – whether we want it or not.

An automatic survival mechanism, the fight or flight stress response involves a cascade of biological changes to prepare us for emergency action.

A small part of the brain called hypothalamus sets of a chemical alarm. The symphathetic nervous system responds by releasing a flood of hormones (such as adrenaline, norepinephrine and cortisol) which race through the bloodstream making us ready to either flee the scene or battle it out.

Sometimes this automatic mechanism is called ‘fight, flight or freeze’ response referring to the situation when one freezes in the face of a life-threatening (or perceived) danger.

While all of these physiological changes are happening for a good reason, they can be really harmful to our health if they remain to stay with us for long and if we lack a successful coping strategy to deal with the symptoms.


Below is an incomplete list of the changes that take place in the body:

Eye-sight: pupils dilate to allow for more focused vision (tunnel or sharper vision).

Blood pressure: heart rate increases to send blood quickly to areas where it is needed.

Breathing: breath becomes quicker and shallower to take in more oxygen to power the muscles.

Immune system: repressed to save energy for prioritized functions such as running.

Perspiration (sweating): increases so that the body can cool down and burn more energy. A cool machine is an efficient machine, so sweating makes the body more likely to survive a dangerous event.

Digestion: decreases so that the blood can be directed to the brain and muscles. This can lead to feelings of nausea or butterflies in the stomach.

Muscles: become tense all over the body to get them ready for run or fight. Muscles may also shake or tremble, particularly if you stay still, as a way of using up excess adrenaline.

Bladder urgency: muscles in the bladder sometimes relax in response to extreme stress.

Hands: get cold as blood vessels in the skin contact to force blood towards major muscle groups.

Thoughts: Quicker thinking helps to evaluate danger and make rapid decisions. It can be very difficult to concentrate on anything apart from the danger or escape routes. If we fail to use up the extra oxygen (by moving or fighting) we can quickly start to feel dizzy or light-headed.

Mouth: becomes dry. The mouth is part of the digestive system. Digestion shuts down during dangerous situations as energy is diverted towards the muscles.