- Oneiroid syndrome (OS), or dream-like fantastic delusional derangement of consciousness, is characterized by a kaleidoscopic quality of psychopathological experiences, wherein reality, illusions and hallucinations are merged into one. It is typically accompanied by motor and, in particular, catatonic disturbances. This syndrome is an uncommon psychiatric state, which is hardly mentioned in standard psychiatric textbooks. OS is a neglected entity among DSM-oriented psychiatrists because it deals with a phenomenological approach in contrast to the European attitude, which deals with detailed clinical descriptions. Here, we propose detailed clinical descriptions with a number of consecutive stages of the OS development, illustrated by two vignettes with typical variants of oneiroid syndrome, in order to raise the awareness of psychiatrists who are not familiar with this state, and to try to open a window to the inner life of those patients suffering from this syndrome. These cases may also serve as illustration of certain principles which, when understood, may be found to lead in turn to a deeper knowledge of the psychopathology of other more commonplace conditions.