Abstract
BackgroundSleep dysfunction is extremely common in patients with schizophrenia. Recent research indicates that sleep dysfunction may contribute to psychotic experiences such as delusions and hallucinations. ObjectivesThe review aims to evaluate the evidence for a relationship between sleep dysfunction and individual psychotic experiences, make links between the theoretical understanding of each, and highlight areas for future research. MethodA systematic search was conducted to identify studies investigating sleep and psychotic experiences across clinical and non-clinical populations. Results66 papers were identified. This literature robustly supports the co-occurrence of sleep dysfunction and psychotic experiences, particularly insomnia with paranoia. Sleep dysfunction predicting subsequent psychotic experiences receives support from epidemiological surveys, research on the transition to psychosis, and relapse studies. There is also evidence that reducing sleep elicits psychotic experiences in non-clinical individuals, and that improving sleep in individuals with psychosis may lessen psychotic experiences. Anxiety and depression consistently arise as (partial) mediators of the sleep and psychosis relationship. ConclusionStudies are needed that: determine the types of sleep dysfunction linked to individual psychotic experiences; establish a causal connection between sleep and psychotic experiences; and assess treatments for sleep dysfunction in patients with non-affective psychotic disorders such as schizophrenia.
Highlights
Psychotic disorders such as schizophrenia have been associated with sleep dysfunction since first clinically described
The majority of studies utilise subjective reports of either insomnia symptoms (8 papers) or other sleep disturbances such as nightmares (7 papers), while the remaining three papers focus on sleep deprivation
In national epidemiological surveys, a diagnosis of insomnia was associated with odds ratios (OR) of 1.78–2.54 for reporting concomitant paranoia (Freeman et al, 2011), with chronic insomnia linked to a 5 times increased likelihood of endorsing the statement ‘a group of people are plotting to cause you serious harm or injury’ (Freeman, Brugha, et al, 2010)
Summary
Psychotic disorders such as schizophrenia have been associated with sleep dysfunction since first clinically described. Patient accounts show awareness of an interaction between their psychotic experiences and their sleep: “They [the voices] keep me from going to sleep”; “the more tired I am the worse they get” (Waite et al, 2015). It is only in the last few years that a research agenda has emerged concerning sleep dysfunction as a putative contributory causal factor and therapeutic target in the occurrence of psychotic experiences (Freeman, Pugh, Vorontsova, & Southgate, 2009; Freeman & Waite et al, 2015; Harvey & Murray, 2011; Wulff, Gatti, Wettstein, & Foster, 2010). Conclusion: Studies are needed that: determine the types of sleep dysfunction linked to individual psychotic experiences; establish a causal connection between sleep and psychotic experiences; and assess treatments for sleep dysfunction in patients with non-affective psychotic disorders such as schizophrenia
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