Introduction: "The term stress has become very popular in recent years. Although widely used, it is still ambiguous. It is applied when referring to uncommon, traumatic events, but also with regard to everyday life situations and related experiences. The concept of stress is derived from the works of physiologist Walter Cannon and endocrinologist Hans Selye and concerns primarily biological stress considered in terms of reactions to present stimuli. Any symptoms of maladjustment or lack of adaptation are treated as indicators of stress. Cannon used the term stress to describe the ‘fight or flight’ response triggered to restore the disturbed balance of the body as a result of the activity of disruptive stimuli."(...)