Dissociative amnesia is characterized by extensive but selective memory loss that has no known organic cause (e.g., head injury). This disorder is often associated with an overwhelming stress. Part of dissociative amnesia is dissociative fugue.
Depersonalisation Derealisation disorder: dreamlike state has a sense of being separated from self and reality. There is a change of self-perception and the person’s sense of reality is temporarily lost or changed.