Anxiety disorder can be cause by major accident or event such as serious injury or sexual assault.
Recent research shows that chronic insomnia can be cause by anxiety and depression. Lack of sleep develop the feeling of anxiousness in human.
Anxiety disorder can be cause by stressful life situation, such as death of a loved one or divorce.
Anxiety disorder can be cause by imbalance brain chemicals through stress and drugs.
Heredity is very strong term of anxiety disorder. Anxiety disorder has some genetic link such as sensitive parents raise more anxious child.
Anxiety can be caused by alcohol abuse, caffeine, benzodiazepine can worse cause anxiety. Some physical diseases lead to anxiety disorder, such as hyglycemia (blood sugar level is too low).