Sleep in schizophrenia: A systematic review and meta-analysis of polysomnographic findings in case-control studies

Polysomnographic studies have been performed to examine the sleep abnormalities in schizophrenia, but the results are inconsistent. An updated systematic review, meta-analysis, and moderator analysis was conducted. Major databases were searched without language restriction from 1968 to January 2014. Data were analyzed using the random-effects model and summarized using the Hedges's g. Thirty-one studies with 574 patients and 515 healthy controls were evaluated. Limited by the number of studies and a lack of patient-level data, moderator analysis was restricted to medication status, duration of medication withdrawal, and illness duration. We showed that patients with schizophrenia have significantly shorter total sleep time, longer sleep onset latency, more wake time after sleep onset, lower sleep efficiency, and decreased stage 4 sleep, slow wave sleep, and duration and latency of rapid eye movement sleep compared to healthy controls. The findings on delta waves and sleep spindles were inconsistent. Moderator analysis could not find any abnormalities in sleep architecture in medication-naïve patients. Patients with antipsychotic withdrawal for longer than eight weeks were shown to have less sleep architectural abnormalities, compared to shorter duration of withdrawal, but the abnormalities in sleep continuity were similar. Slow wave sleep deficit was found in patients with schizophrenia for more than three years, while sleep onset latency was increased in medication-naïve, medication-withdrawn, and medicated patients. Our study showed that polysomnographic abnormalities are present in schizophrenia. Illness duration, medication status, and duration of medication withdrawal are several of the clinical factors that contribute to the heterogeneity between studies.