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What is stress?

Stress is caused by two things. Primarily it is down to whether you think situations around you are worthy of anxiety. And then it's down to how your body reacts to your thought processes. This instinctive stress response to unexpected events is known as 'fight or flight'.

Stress happens when we feel that we can't cope with pressure and this pressure comes in many shapes and forms, and triggers physiological responses. These changes are best described as the fight or flight response, a hard-wired reaction to perceived threats to our survival. When survival had meant facing immediate and real threats such as confronting a charging elephant, our response has saved lives.

At times of danger, the body's innate intelligence automatically takes charge by triggering a set of changes that bypass our rational thoughts. Priority is given to all physical functions which provide more power to face an enemy or to flee. To understand why stress can have negative impacts on your health, you must first understand the physiological changes that occur within your body during the fight or flight response.

Fight or flight
The fight or flight response was first noted by one of the early pioneers in stress research, Walter Cannon. In 1932 he established that when an organism experiences a shock or perceives a threat, it quickly releases hormones that help it to survive.

In humans, as in other animals, these hormones help us to run faster and fight harder. They increase heart rate and blood pressure - delivering more oxygen and blood sugar to power important muscles. They increase sweating in an effort to cool these muscles, and help them stay efficient. They divert blood away from the skin to the core of our bodies - reducing blood loss if we are damaged. As well as this, these hormones focus our attention on the threat, to the exclusion of everything else. Breathing is accelerated to supply more oxygen for conversion to energy. The heart moves into overdrive to supply the body with more oxygen and nutrients. Our immune system is activated, ready to administer to wounds. Attention and sight become acute and highly focused and our sense of pain is diminished as the body releases analgesic hormones.

This physiological aspect leaves us viewing the world as a hostile place and we are fully prepared to fight or run. Whichever one we choose, our body will expend an immense amount of energy which in itself prevents the build up of stress related to this response.

Modern civilisation mostly provides a shield against predators. Charging elephants are a less likely concern, unless you happen to be living the natural life in the jungle full of rampaging pachyderms. The inherent fight or flight response still resides in us but now it is triggered by different, seemingly less life threatening events. Many day-to-day situations can set it off - a change of home, a difficult boss, divorce, separation, demanding children, traffic jams, the fear of terrorism etc.

The more often we are exposed to these types of stressors, the more overactive our fight or flight response becomes until we find ourselves operating at fever pitch level, constantly prepared for battle, perceiving potential threats everywhere. That is why people who are over stressed not only show physiological symptoms such as high blood pressure, rapid heart rate or shallow fast breath; they can seem overly sensitive or aggressive. Today many of us don’t take enough physical exercise to ‘burn off’ the effects of our response and we’re left with stress build up. We learn to control our reactions, but this does not counteract the stress response.

Life-threatening events are not the only ones to trigger this reaction. We experience it almost any time we come across something unexpected or something that frustrates our goals. When the threat is small, our response is small and we often do not notice it among the many other distractions of a stressful situation.


Unfortunately, mobilising the body for survival has negative consequences too. We are excitable, anxious, jumpy and irritable. This reduces our ability to work effectively. With trembling and a pounding heart, we can find it difficult to execute precise, controlled skills. Focusing on survival means we make decisions based on the good of ourselves rather than the good of the group. We shut out information from other sources and cannot make balanced decisions.