Depersonalization after brain damage is still only rarely reported and poorly understood. We describe three patients between the ages of 21 and 25 who experienced depersonalization and derealization for periods of 6 weeks to 4 months, two after traumatic brain injury, the third after surgical and radiation treatment of a pineocytoma. Each one believed to be living in a nightmare and thought about committing suicide in order to wake up. One patient developed symptoms as described in Cotard delusion. Aspects of neuroanatomy, psychodynamics, and anthropology are discussed with reference to the literature. Frontal and temporal lesions seem only to play a facilitating role but not to be a necessary condition. There is evidence for additional influence of psychological and premorbid personality factors. Summarizing the current state of information we consider depersonalization with the experience of being in a dream or being dead as a heuristic reaction to brain damage. Similar models have already been discussed in neuropsychological disorders as for instance reduplicative paramnesias, neglect, and anosognosia.