The effect of stressful emotion on the body and mind is now being carefully studied by scientists, as more and more people all over the world fall ill and die due to stress-related diseases.
In a stressful situation, the adrenal glands automatically secrete hormones like adrenaline, which mobilizes all the organs of the body for extreme exertion to either fight or flee. This instinctive response is a legacy of our primitive past; for when out early ancestors faced dangerous situations they dealt with them in burst of intense physical exertion until the stress was over–either fleeing rapidly from predatory animals or clubbing an enemy into unconsciousness. But contemporary human beings can neither flee from their problems nor physically battle their adversaries, and thus face continual and unrelenting stresses which they cannot respond to with physical activity.
The employee who is constantly criticized by his boss, the student under constant pressure of excess homework and exam deadlines, the harried housewife, all build up intense inner tensions. Emotions like anger send shock waves through their nervous systems and their muscles tense, their breath becomes irregular and their fists clench. Their blood pressure increases, their hearts race, and their digestion is impaired. But although they are prepared for a burst of activity, they cannot physically release this tension by hitting someone over the head or running away, so they bottle it up inside. Their overstimulated adrenal glands maintain their bodies and minds in a state of perpetual alarm and inner tension, and as a result they develop melanchol, depression and anxiety neuroses, even as early as grade school. This prolonged stress depresses the immune system and lowers the resistance to infection and disease, and this often results in disease, stomach ulcer, asthma, migraine headache, arthritis, and even cancer.
Source: “Stress and Adrenal Glands”, from Yoga for Health, by Didi Anandamitra Acarya