Anxiety is a normal human response to unpleasant and potentially dangerous events. Evolutionarily, this reaction has arisen so that we can mobilize and act quickly. In some cases, anxiety can actually help. For example, in a dark alley, she will make you look around, avoid suspicious figures and speed up if the situation seems dangerous. Anxiety occurs during times of change, before important tests or meetings - and at a moderate level helps to concentrate, exert more effort, and better adapt.