Sleep disturbances in individuals at clinical high risk for psychosis

Highlights

• CHR patients are significantly more sleep disturbed than healthy controls.

• The relationship between sleep disturbance and symptoms in the patient population is significant.

• Sleep disturbance item 4 and 5 (functioning impacted and day/night reversal) were related to greater positive symptoms.

• These two item 3 (daytime fatigue) were also significantly predictive of negative symptom severity.

• Sleep disturbance item 4 (sleep pattern disruption) was related to worse overall functioning.

Abstract

There has been recent interest in understanding the role that sleep disturbance plays in patients at Clinical High Risk for psychosis (CHR). We assessed sleep disturbance in 194 CHR patients and 66 healthy control subjects and their relationship to symptoms (positive, negative and general functioning). Patients experienced significantly more sleep disturbance than healthy control subjects and their sleep disturbance was related to greater positive and negative symptoms and worse overall functioning. Targeting sleep disturbance in CHR individuals may provide alternative means of treating the CHR syndrome.

Introduction

Schizophrenia and other psychoses are characterized by positive and negative symptoms, as well as functional impairments. Attenuated positive symptoms, negative symptoms, and other general psychiatric symptoms may be present for a period of time prior to the onset of threshold psychosis, and are assessed using the Structured Interview for Psychosis-Risk Syndromes (SIPS) (Miller et al., 2003). One general symptom is sleep disturbance, which is observed in a large number of patients with schizophrenia, approximately 30–80% (Cohrs, 2008). Even so, sleep disturbance is characteristic of many disorders, and is not always a focus of treatment. With better characterization of the relationship between sleep disturbance and symptoms, there is hope that sleep disturbance particular to CHR patients could be targeted as a means of preventing conversion to psychosis.

The mechanism by which sleep interacts with other known risks for psychosis is unclear, although evidence does suggest that individuals with schizophrenia with sleep disturbance experience more severe symptoms than patients without (Afonso et al., 2014). In a cross-sectional study, Afonso et al. (2014) compared 811 schizophrenia outpatients based on whether or not they had sleep disturbance. Quality of sleep, symptom severity, adherence to treatment, and degree of family support were variables of interest. Patients with sleep disturbance were significantly more symptomatic and were found to have worse compliance and less family support than patients without disturbance. These findings suggest that the presence of sleep disturbance is an important clinical factor that may modify the presentation of psychosis. However, whether patients with sleep disturbance experience this extra level of dysfunction and symptom severity as a result of sleep disturbance or as a precursor to was not necessarily addressed in the aforementioned study.

Sleep disturbance has been described earlier in the disease process as well. Specifically, it is one of the most common prodromal features preceding a first episode of psychosis or psychosis relapse (Yung and McGorry, 1996). In a retrospective study investigating first-episodes of psychosis, sleep disturbance preceded first episode psychosis in the majority of patients (Tan and Ang, 2001). Others have reported a relationship between sleep disturbance and conversion to psychosis (Ruhrmann et al., 2010). While these studies shed light on the presence of sleep disturbance in early psychosis, they emphasize sleep disturbance as an important symptom that often occurs before conversion.

In one study, Lunsford-Avery et al. (2013) reported that, in 33 patients at ultra high risk for psychosis, patients had greater latency to sleep onset and greater disrupted continuity of sleep than controls. They found relationships between sleep disturbance and greater negative symptoms but not positive symptoms.

Studies that examine a general population and assess for psychotic-like experiences have also reported relationships between symptoms and sleep disturbance. A cross sectional study which questioned over 7000 adolescents about psychotic like experiences and sleep showed very strong relationships between sleep disturbance and psychotic like experiences (Lee et al., 2012). Taylor et al. (2015) assessed sleep, using the Pittsburgh Sleep Quality Index and Insomnia Severity Index, and psychotic like experiences in a general population of twins and found associations between sleep disturbance and positive symptoms. They found an association between sleep disturbance and negative symptoms as well, though the association was not as large. Day/night reversal is a well documented sleep disturbance in individuals with schizophrenia (Wulff et al., 2012).

Fisher et al. (2014) interviewed 6796 children and their parents from the general population at sequential time intervals to assess parasomnias and their relationship to psychotic-like experiences in childhood. The authors found that children who experienced frequent nightmares from ages 2.5 years to 9 years were more likely to experience psychotic-like symptoms at age 12 years. They also reported that 12 year old children reporting parasomnias were nearly four times as likely to have concurrent psychotic-like experiences than 12 year old children not reporting parasomnias.

These previous findings are helpful in that they suggest the prevalence and importance of sleep disturbances as they relate to attenuated psychotic symptoms. The goals of this study are to expand upon these results by examining sleep disturbance in a large CHR population and their relationship with positive and negative symptoms and overall functioning as measured by the SIPS. We hypothesize that sleep disturbance will be present in a CHR population and will be related to greater symptoms and worse functioning. In addition we hypothesize based on the literature that day/night reversal (sleep item 5) would be related to positive symptoms and that CHR subjects would have significantly great sleep disturbance than controls.