# Sleep a Potential Treatment Target for Schizophrenia?
A new analysis reveals a bidirectional relationship between sleep patterns and schizophrenia, leading researchers to suggest that sleep may be a potential treatment target for the disorder.
Applying a Mendelian randomization (MR) approach, the investigators selected genetic variants from a meta-analysis of genome-wide association studies (GWAS) conducted using data from UK Biobank and 23andMe. They found that morning diurnal preference was associated with a lower risk for schizophrenia. In contrast, long sleep duration and daytime napping were associated with a higher risk for schizophrenia.
Conversely, genetically predicted schizophrenia was negatively associated with morning diurnal preference and short sleep duration, whereas it was positively associated with daytime napping and longer sleep duration.
“Our MR study revealed that morning diurnal preference was associated with a lower risk of schizophrenia; in addition, our results supplied clues for the causal relationship between long sleep duration and a higher risk of schizophrenia, between daytime napping and a higher risk of schizophrenia,” write the investigators, led by Zhen Wang of the Department of Cardiovascular Surgery, School of Medicine, First Affiliated Hospital of Zhejiang University, Hangzhou, China. “Therefore, sleep traits were identified as a potential treatment target for patients with schizophrenia,” they add.
The study was published online on June 15 in BMC Psychiatry.
Underrecognized Therapeutic Target
About 80% of patients with schizophrenia experience widespread sleep abnormalities. However, sleep continues to be an “underrecognized therapeutic target in clinical practice,” the investigators note. They point out that most meta-analyses suggest "potential causal associations between sleep dysfunction and schizophrenia. However, they add, causality is “difficult to confirm.”
MR “uses genetic variants as instrumental variables to investigate the causal association between exposures and outcomes.” The researchers consider MR as a “natural randomized controlled trial” because genetic variants are randomly inherited.
Therefore, they add, MR offers an “alternative approach to explore the potential causal relationship between an exposure and an outcome when RCTs are not feasible” and are useful for investigating the bidirectional causal relation between sleep traits and schizophrenia.
Exposures and Outcomes
The sleep traits that the researchers examined included morning diurnal preference, long and short sleep duration, daytime sleepiness, daytime napping, and insomnia.
The researchers obtained genetic summary statistics for exposures and outcomes by selecting variants from a meta-analysis of GWAS conducted using data from the UK Biobank and 23andMe.
Although they used summary statistics from European individuals in the UK Biobank (n = 449,734), the genetic loci that they included in some of the analyses were taken from both data sources.
Genetic loci identified in the meta-analysis and used by the researchers in the current study are listed below. Shift workers and those with chronic and psychiatric disorders or other poor health were excluded from some of the analyses.
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