Anxiety, which can be described as a state of excessive worry, apprehension and restlessness, is one of the states most commonly experienced by people. When confronted with a threat, people feel a high level of apprehension. At the same time fight or flight reactions set in when the nervous system is strongly stimulated. These establish themselves as sweating, shivering, hot flushes, numbness, palpitations, a feeling of suffocation, alienation. They are produced by the sympathetic nervous system whose task is to deal with danger.