Dreams, hallucinogenic drug states, and schizophrenia: a psychological and biological comparison.

Many observers have noted similarities between dreams, hallucinogenic drug states, and schizophrenia. In the present article, certain fundamental areas of convergence between the three states are described. Consideration is given to the hallucinogenic drug model of psychosis: the reasons for its initial attractiveness, and the reasons for its current disfavor. The concept of ego boundaries is defined, examined, and applied to the three states. In these states, the ego's capacity to average or synthesize various self-representations into a continuous, coherent self is compromised--leading to an impairment of the reality-oriented secondary process, and the emergence of the florid attributes of the primary process. This can account for many of the familiar characteristics of the three states. Current neurophysiological theories of dream and hallucinogenic drug states are presented, with emphasis upon serotonin neurotransmission. Serotonin appears to play a prominent role in the regulation of these states. The analogy contained in the present article suggests that serotonin may play a role in regulating schizophrenic states as well.