There are two types: the type that is good, making you feel satisfaction and happiness. And there is negative, which leads to fatigue and possibly, illness.
There is no singular thing to point to as a cause of the latter. But, what is known about it is that the body makes biochemical changes when it is present.
GAS or General Adaptation Syndrome, has three stages. These stages are: alarm, resistance, and exhaustion. In the alarm stage the quick initial response is lowered blood pressure and tachycardia. This is in preparation for the fight or flight response to continued stress. The body will continue to increase its production of adrenocortico-tropic hormones. Along with this is increasing heart rate and elevation in blood pressure.
If the condition becomes prolonged, to the point where the adaptation of the body is too great, vulnerability of the body occurs…and exhaustion. The body is not designed to stay in a heightened state of arousal.
If continued, the sympathetic nervous system becomes activated with vasoconstricted blood vessels, increasing blood pressure, increasing heart rate, and the secretion of adrenaline. The immune system will then become suppressed and the increasing cortisol will cause cholesterol and other lipids in the blood to increase at the same time.
Situations or “agents” that cause stress are called STRESSORS. These may include physical things such as heat, exertion, trauma, infection, or cold. Or it may be from psychological reasons such as fear, anxiety, or disappointment. Stress may be caused by external things. Examples may include poverty, inadequate housing, and certain life events.
Factors altering stress responses are called mediators. The MEDIATORS may be genetics, developmental factors, experience, and social context. Some people appear to be more resilient and cope better with stress, while others seem to be more vulnerable.