Fight or flight is the psychological response to how we respond to stressful situations. Your body releases hormones that prepare your body to either stay and deal with the situation or leave it. The saying derives from our ancestors about when they faced danger or threats in their environment and whether they would fight or flee, e.g. taking it back to prehistoric times, if a caveman was threatened by a predator, they would either fight and defend their home or flee for safety.

The chemical reaction of fight or flight works like this… the sympathetic nervous system stimulates the adrenal glands. This releases catecholamines including adrenaline and noradrenaline. An increase in heart rate, blood pressure and breathing then follows, prepping for fight or flight.