All animals including human beings possess this innate mechanism and its response, which prepares one for fight, or flight is involuntary. When stressful situation regularly recurs, the stress-mechanism is repeatedly activated. If the physiological conditions described above persist over a long time or frequently recur, serious disorder would occur.
Thus, if blood- pressure remains high and blood-vessels get constricted, it will result in heart-attacks or strokes; if the impoverished blood-supply to stomach is prolonged, there will be digestive disorders; if the breathing is prolonged at a high rate, it may result in asthma etc., sustained muscle tensions will bring aches and pains in the head, back, neck and shoulders. Besides these, chronic tension may also bring feelings of panic which is irrational fear and which can be not only frightening but also crippling.
Tense, nervous and anxious modern man is driven inexorably into stress because his constant state of anxiety prevents him from coping up with the relentless demands of modern life. There is plenty of evidence now to show that tension may play a significant part in promoting or triggering off a great many illnesses. If we are to solve successfully the problem of stress, we have to find a way of allowing the parasympathetic to function efficiently, so that it can establish the equilibrium and harmony, which has been destroyed.