Derealization is a symptom of a number of psychiatric illnesses. Derealization can occur as a result of severe anxiety or despair. Derealization can occur in those who are experiencing panic attacks as a result of anxiety disorders or memories as a result of posttraumatic stress. Derealization is a typical symptom of dissociative disorders and may be present in some forms of schizophrenia. An individual may also feel the symptom during or shortly after a distressing event. Depersonalization and derealization can also be caused by brain injury to the temporal or occipital lobes. Derealization can be aided by drugs like marijuana, hallucinogens, pain relievers, and even heavy doses of coffee.