Isolated sleep paralysis and hypnic hallucinations in schizophrenia

In a cross-sectional survey of 71 people with schizophrenia or schizoaffective disorder receiving follow-up care from an Assertive Community Treatment Team, only 15% reported sleep paralysis and 16.9% reported hypnic hallucinations, a considerably low prevalence. The authors conclude that studying these phenomena in patients with active or residual symptoms of schizophrenia is difficult and that more refined studies and appropriate questionnaires are needed. They also note that the possibility of sleep paralysis and hypnic hallucinations confounding or being misdiagnosed as psychotic symptoms should be considered.

Study at a glance

Abstract

Background: Usually remembered in the context of Narcolepsy-Cataplexy syndrome, isolated sleep paralysis (SP) and hypnic hallucination are widely prevalent and because of the overlap of symptoms with schizophrenia, their identification is important but unrecognized. Aims: To determine the presence of SP and hypnic hallucinations (HH) in people with schizophrenia and schizoaffective disorder Study Design: Cross-sectional survey. Methods: Participants were patients receiving follow-up care for schizophrenia from Assertive Community Treatment Team. A screening questionnaire was administered during their routine follow-up visits. Results: Of 71 respondents (49 males, 22 females) only 11 (10 males and 1 female), that is, 15% reported SP, and 12 (7 males and 5 females), that is, 16.9% reported HH, a considerably low prevalence. Conclusion: It is difficult to study the presence of SP and HH in patients with active or residual symptoms of schizophrenia, and more refined studies and appropriate questionnaires are required. The possibility of SP and HH confounding or being misdiagnosed as psychotic symptoms needs to be borne in mind.