Holistic Sleep Experiences Crucial to Understanding Psychosis
Accounting for social anxiety and depressive symptoms, it seems the combination of perceived poor sleep and an actual lack of sleep predicts the greatest risk in psychotic experiences.
Assessing patients' risk for psychosis requires holistic consideration of their sleep experiences rather than relying solely on patients' subjective reports of sleep or only 1 or 2 cursory questions about consistent bedtimes or total sleep time, suggests emerging research.
The link between psychosis and poor sleep and circadian rhythm disruptions has long been established in the evidence base, with at least 1 study finding that 30% to 80% of patients with schizophrenia experience sleep problems.1
Far less research, however, has teased out specific relationships between different subjective and objective sleep measures and prodromal psychosis or risk for psychosis. The studies that have been performed suggest that subjective and objective sleep interact in predicting the risk for psychosis.
"There's an important role for looking at objective sleep, especially with schizophrenia and psychosis," Jan Cosgrave, PhD, a Fulbright visiting scholar at the University of Pennsylvania Perelman School of Medicine in Philadelphia, told Psychiatry Advisor. Clinicians often ask about subjective sleep, as they should, she says, but they need to ask patients about more than just perceived sleep experiences, particularly objective sleep.
Dr Cosgrave's research, including a recent study of psychosis in 43 healthy young adults, has found that objective measures of sleep and subjective perceptions of sleep do not always correspond, although their interactions influence the risk for psychosis.2
"If I have a really good perception of sleep, the number of objective hours of sleep doesn't matter that much," Dr Cosgrave noted, based on the findings of this study. "But if I manipulate the perception of sleep, all of a sudden those hours of objective sleep as measured by actigraph become more important. The less of those objective sleep hours they get, the higher their risk for psychosis is."
Subjective and Objective Sleep Interact to Affect Risk for Psychosis
In Dr Cosgrave's study, published in Schizophrenia Research, symptoms of sleep and psychosis were assessed in 21 college students (aged 18-30 years) with insomnia and 22 control patients.2 They used the Pittsburgh Sleep Quality Index scores (scale, 0-21, with 8 and above indicating poor sleep), the Insomnia Severity Index (scale, 0-28, with 10 and above indicating insomnia), and the Prodromal Questionnaire 16 Item Version (scale, 0-16, with 5 and above indicating need for further assessment for psychosis).
The average Pittsburgh Sleep Quality Index scores were 10.1 in the insomnia group and 2.4 in the control group, and the average Insomnia Severity Index scores were 14.4 in the insomnia group and 1.3 in the control group. The median Prodromal Questionnaire 16 Item Version scores were 3 in the insomnia group and 1 in the control group.
The researchers analyzed relationships among these scores, a standardized diary of sleep and daytime activities, and the following objective sleep measures as assessed by 3 weeks of wrist-worn actigraphy: sleep fragmentation, sleep onset latency (time between going to bed and falling asleep), wake after sleep onset, total sleep time, and variability in sleep onset and sleep duration.
They identified an interaction between the Pittsburgh Sleep Quality Index subjective sleep measures and total sleep time, but "the impact of [total sleep time] and subjective sleep quality on psychotic experiences is different for the insomnia group as opposed to the control group," the researchers reported.
"If sleep quality is perceived as good, our model suggests a perception of good quality of sleep offers sufficient protection from psychotic-experiences," even with under 7 hours of sleep a night, they found. Participants who perceived their quality of sleep as poor but got at least 7.5 hours of sleep a night had negligible risk for psychotic-like experiences, similar to those who perceived their sleep as good.
"[H]owever, with decreasing hours of sleep this risk progressively starts to increase," the researchers wrote. "[A]ccounting for social anxiety and depressive symptoms, we find the combination of perceived poor sleep and an actual lack of sleep predicts the greatest risk in psychotic experiences."
Digging Deeper Into Poor Sleep and Specific Psychotic Symptoms
Dr Cosgrave is now trying to examine whether different types of poor sleep, objective and subjective, influence specific types of psychotic symptoms. So far, for example, her research suggests that sleep disturbances are more connected to dissociative experiences than to other psychotic symptoms, at least in healthy subjects.
It is premature to attempt to extrapolate findings from current studies, mostly involving healthy participants, to people with schizophrenia and people of diverse demographics. However, identifying possible causal or bidirectional pathways can set the stage for research into understanding relationships in those with schizoaffective disorders. It can also lead to learning more about the effect of sleep interventions.
"It's safe to assume poor sleep can make psychosis worse, and that transcends the schizoaffective spectrum," Dr Cosgrave told Psychiatry Advisor.
Whether poor sleep alone can directly cause psychosis is unknown, and probably unlikely, although identifying poor sleep patterns early enough in someone at risk for psychosis may provide an opportunity for intervention that prevents hospitalization, she surmised.
In a recent review of the evidence on sleep, circadian rhythms, and schizophrenia, Dr Cosgrave found "good evidence for a cause-and-effect relationship between sleep and subclinical psychotic experiences."3 What's less clear, however, is whether interventions to improve sleep necessarily improve symptoms of psychosis. It may do so in the general population, but not in those with clinical diagnoses of psychosis.
"It would appear treating insomnia improves psychotic experiences in an insomnia cohort but not in a cohort with schizophrenia," Dr Cosgrave and her colleagues reported in that review, published in Current Opinion in Psychiatry.3
The strongest evidence for improvement in healthy subjects is a large study published in Lancet Psychiatry that randomly assigned 3755 students to receive cognitive behavioral therapy for insomnia (CBTi), which is the insomnia intervention with the strongest evidence, or usual care for insomnia.4 At 10 weeks, the CBTi group experienced less insomnia and fewer subclinical paranoia and hallucinations, with insomnia mediating the reduction in those symptoms.
However, attempting to treat insomnia in people with schizoaffective disorders is tricky because CBTi involves sleep restriction, which is counterindicated in people with schizoaffective disorders.
"The thing with CBTi is that we don't know yet if you can do sleep restriction safely in people with psychosis," Dr Cosgrave told Psychiatry Advisor, and sleep restriction is likely 1 of the most effective parts of CBTi.
Although researchers continue learning about specific interactions between poor sleep and psychotic symptoms, clinicians should be incorporating more comprehensive questions about sleep into their assessment of patients, Dr Cosgrave said.
"The take-home message is always remember to ask about sleep and always remember to ask beyond basic questions about sleep quality," she told Psychiatry Advisor. Ask about sleep timing and regularity of sleep timing (whether bedtimes shift and how), napping behaviors, and unusual sleep experiences that potentially indicate a sleep disorder, such as rapid eye movement problems or excessive snoring, a symptom of sleep apnea. "Make sure to rule out your differential diagnoses within sleep, and not just ask about basic questions that would target insomnia," Dr Cosgrave said.
Disclosures: Dr Cosgrave and her research were funded by the Medical Research Council, the National Institute for Health Research, the Wellcome Trust, and Oxford University. Coauthor Philip Gehrman in the research review reported a previous grant from Merck. No other authors had disclosures to report.
1. Cohrs S. Sleep disturbances in patients with schizophrenia. CNS Drugs. 22(11):939-962.
2. Cosgrave J, Haines R, van Heugten-van der Kloet D, et al. The interaction between subclinical psychotic experiences, insomnia and objective measures of sleep. Schizophr Res. 2018;193:204-208.
3. Cosgrave J, Wulff K, Gehrman P. Sleep, circadian rhythms, and schizophrenia: where we are and were we need to go. Curr Opin Psychiatry. 2018;31(3):176-182.
4. Freeman D, Sheaves B, Goodwin GM, et al. The effects of improving sleep on mental health (OASIS): a randomised controlled trial with mediation analysis. Lancet Psychiatry. 2017;4(10):749-758.