Selye's GAS Theory

Selye's GAS theory discovered that human and non human animals respond to stressors in a similar way. He found that the health of rats deteriorated in the same way every time they underwent an operation or were injected with noxious drugs. The pain they experienced was not what killed them, it was the body's response to the stressors. He found that humans also reacted in a similar way.

He therefore suggested that our responses to stress happens in 3 stages: alarm, resistance and exhaustion. This is based on the assumption that our behaviour is caused by our physiology and that the stress response is biologically determined. 

During the alarm stage, we become aware of a stressor…