Normal anxiety is part of the innate natural defence system, so when working properly, it raises one's awareness of some kind of threat or danger, so that one can be prepared to deal with it and then to settle down. But one can become stuck in a state of constant anxiety for various reasons. Often the reasons are to do with unresolved experience(s) from the past, or perhaps a lack of ongoing felt security in childhood. It is as if a part of the self cannot let one relax because it has the job of keeping one in a state of hyperarousal, as if one's present safety depended on it. Psychotherapy, in resolving the roots of the anxiety that has become stuck, can help the person's natural role of anxiety to be restored as a useful, occasional raising of tension and readiness for action whenever appropriate.
Ongoing high levels of anxiety can have serious effects on the body's metabolism, and one's energy levels.
Various physical conditions have been linked with ongoing high levels of stress and anxiety, including, heart attacks, high blood pressure, strokes, ulcers, rheumatoid arthritis, insomnia, and muscle tension.