Sleep and Cognition in Schizophrenia

Abstract

Background and Objective: Schizophrenia (SCZ) affects both genders with similar rates. It usually appears in the second to the third decades of one’s life. Schizophrenia is marked by a wide spectrum of symptoms, which functionally impair patients. The symptoms are categorized as positive, negative, or cognitive deficits. Among them, cognitive disturbance is highly valued. However, the relationship between sleep and cognition in patients with schizophrenia has been less widely considered. In this study, we aimed to review the relationship between sleep and cognition in patients with schizophrenia. Materials and Methods: We considered selected key words (e.g. Cognition, Schizophrenia, and Sleep), and searched the online databases at the first step with defined time window of 2010 to the present; while at the second step, the incomplete knowledge was completed from 1990 to 2010. Among them, articles related to our research objectives were selected for further review. Results: Cognitive functions including memory, attention, reasoning, decision-making, and many other elements are tightly related to quality of sleep. Moreover, sleep deficit exacerbate the symptoms of schizophrenia. It is known that cognitive function is dependent on certain activities in brain that occur during sleep. A body of research has indicated that the slow wave sleep, rapid eye movement (REM) sleep, K-complex, and also sleep spindle are at least partly explained by these functions. Conclusion: In the light of these findings, study of brain activity via electroencephalogram (EEG) during sleep is a reasonable objective method for assessment of sleep-related cognitive markers in patients with schizophrenia.

Keywords

• Cognition
• Schizophrenia
• Sleep