Best Way to Understand the Fight or Flight Response

People vary enormously in their perception of what is a stressful situation, but the physiological way our bodies respond to something we interpret as a threat – whether physical, mental or emotional, or simply challenging – is the same. Stress activates a part of the brain called the hypothalamus, setting off a complicated chain of biochemical events that causes a rush of adrenaline and noradrenaline into the system, rapidly followed by Cortisol. Within a split second these hormones flood the body and circulate through the bloodstream, reaching all the organs and activating every cell in the body.

At this point our bodies start to work in a different way. The liver releases sugar and fatty acids into the bloodstream to boost energy. We breathe more rapidly, increasing the amount of oxygen in the body. Our hearts beat faster and our blood pressure rises, increasing the circulation of blood to the brain to enable quick thinking and swift decisions, and to the muscles to enable fast action. Our mouths go dry as blood is diverted away to the organs where it is most needed, and we start to sweat – the body’s mechanism for cooling us down. We are now prepared for immediate action: to fight or, if we don’t fancy our chances, to flee.

If the stress response, also known as the fight-flight response, is followed by physical activity, as it was designed to be, the energy released into the system by stress hormones is used up, allowing our bodies to relax and return to their normal state of balance.

This primitive stress response is common to all mammals when confronted with a potentially threatening situation or the sudden appearance of a predator. If a sleeping dog or cat is startled by a sudden noise, it jumps up, hackles raised, ready for action. In a split second it assesses the situation and prepares to fight or take flight or, if satisfied there is no threat, it settles down again and becomes calm. Either way, the stress hormones are metabolized.

What animals do not do is carry on thinking about alarming situations and problems once the immediate danger has passed, so the stress-inducing situations they encounter are interspersed with periods of recovery. Their outer calm is a reflection of their inner calm. We, with our well-developed psyches, are prone to go on and on thinking about anything that is worrying or upsetting us. This inability to switch off is what keeps our stress levels raised, resulting in prolonged or chronic stress.

The fight-flight response evolved over millions of years to deal with emergencies and was very well suited to early man, whose very survival depended on the ability to fight or to escape. It is still vital to our survival, but few of the stresses we are faced with today call for either fight or flight. If stress is prolonged, our bodies remain in a state of physiological arousal with an excess of the stress hormones adrenaline and Cortisol.

It is this unspent energy that causes the damage.