Many of the disorders classified as anxiety disorders involve a feeling of tension or apprehension, or anxiety.
Anxiety is a normal function of normal behavior.
It becomes a disorder when anxiety occurs without any rational, external cause and disrupts daily, normal functioning in life. Phobic Disorders Phobias are irrational fears that interfere with a normal person's functioning. There are a wide list of phobias that have been catalogued already, some of which you may already know of. Acrophobia - Fear of heights. Agoraphobia - Fear open spaces.