Oneiroid syndrome, from the Ancient Greek "ὄνειρος" (oneiros, meaning "dream"), and "εἶδος" (eidos, meaning "form, likeness") is an element of the catatonic form of schizophrenia

Schizophrenia

Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...

and presents with a dream-like or nightmare-like state as a background of intensive psychopathological experiences.

Oneiroid states were first described by the German physician Meyer-Gross in 1928, mainly statistically.

Later in 1961 the Bulgarian psychiatrist S.T. Stoyanov studied the dynamics and the course of the oneiroid syndrome in "periodic", or remittant schizophrenia (ICD-10).

According to this research the syndrome has six stages in its course:

1. initial general-somatic and vegetative disorder
2. delusional mood
3. affective-delusional depersonalisation and derealisation
4. fantastic-delusional and affective depersonalisation and derealisation
5. illusional depersonalisation and derealisation, and
6. catatonic-oneiroid state in the culmination.

The prognosis of oneiroid catatonia is optimal, in comparison with lucid catatonia.