Stress (see more on stress earlier in this volume)

. The impact of stress is very subjective and varies from person to person. What is an exciting event for one person can be very stressful for another. An aroused physiological state is characteristic of both stress and pleasure

. Traditionally, the body's defense system focused on handling an immediate response to a life-threatening event, such as an attack. This involves the release of adrenaline from the adrenal glands as instructed by the hippocampus. The adrenal glands also release cortisol which returns the body to normalcy. Under stress your pulse races, your blood pressure rises and there is a massive release of energy

. Chronic stress dangerously deregulates a system made for short-term responses, ie a few seconds, not years. Continual stress from the workplace, home, etc results in hormones staying too long and doing some harm to the likes of your cardiovascular system, immune system, learning, cognitive thinking, executive functioning, etc

. Under chronic stress, adrenaline creates scars in your blood vessels that can cause heart problems, and cortisol damages cells of the hippocampus, crippling your ability to learn and remember. In severe cases, like catastrophic stress, it can close the system down. For example, the body guard to Princess Di cannot remember events a couple of hours either side of the accident. Similar types of things happen, like forgetfulness, depression (deregulation of the thought processes, including memory, language, quantitive reasoning, fluid intelligence, spatial perception, etc)

. There is a framework that suggests that there are systems that keep the brain and body stable by changing themselves (allostasis). The impact of stress depends upon the interaction between the outside world and our physiological made-up. The body's reaction to stress depends on the type of stress (its duration, severity, previous experience with similar types of stress, etc).

. Stressed and non-stressed brains perform differently. Stressed brains "turn off" and as a result learning, performance degenerates, the immune system is more susceptible, the chance of depression increases, etc.

. It is interesting to note that one of the best indicators of performance is emotional stability at home. Another indicator is balance at work between occupational stimulation and boredom.

. Individually the worst kind of stress is the feeling that you have no control over the situation, ie you are helpless (learned helplessness). Linked with control is degree of predictability. On the other hand, there are situations like knowledge worker, where some uncertainty is a powerful motivator in seeking unique solutions

. Emotional stress has a huge impact on society as it can negatively impact learning, productivity, health, etc. There is a need for people to feel in control of their lives.

. The brain is impacted by stress. Some stress can increase performance temporarily; but long exposure is harmful. The memory of stressful experiences are recorded very promptly in the brain and can be recalled very quickly.

When under significant stress, like a life-threatening situation, the body reacts with extreme visual clarity, tunnel vision. In this situation, our mind drastically limits the range and amount of information that we have to deal with, ie

"... Sound and memory and broader social understanding are sacrificed in favour of heightened awareness of the threat...... senses narrowed: that narrowing allowed focus on the threat..."

Malcolm Gladwell, 2005

Research (Malcolm Gladwell, 2005) has shown that the optimum state of arousal, ie the range in which stress improves performance, is when our heart rate is between 115 and 145 per minute. Over 145, the complex motor skills start to break down; at 175 we see an absolute breakdown of cognitive processing, ie the frontal brain shuts down and the "mammalian brain" takes over, vision becomes more restricted, behaviour becomes inappropriately aggressive, physiological control over non-essential activities ceases (like bowels emptying), blood is drawn from outer muscle layers and concentrated in core muscle mass (this makes the muscles as hard as possible to turn them into a kind of armour that limits bleeding in the event of injury). All this leaves us clumsy and helpless!!!!