Supplementary Material for: Gut Microbiome Composition and Its Association with Sleep in Major Psychiatric Disorders

Introduction: Sleep disturbances are highly prevalent across most major psychiatric disorders. Alterations in the hypothalamic-pituitary-adrenal axis, neuroimmune mechanisms and circadian rhythm disturbances partially explain this connection. The gut microbiome is also suspected to play a role in sleep regulation and recent studies suggest that certain probiotics, prebiotics, synbiotics and fecal microbiome transplantation can improve sleep quality. Methods: We aimed to assess the relationship between gut-microbiota -composition, psychiatric disorders and sleep quality, in this cross-sectional, cross-disorder study. We recruited 103 participants, 63 patients with psychiatric disorders (Major Depressive Disorder n=31, Bipolar Disorder n=13, Psychotic Disorder n=19) along with 40 healthy controls. Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI). The fecal microbiome was analyzed using 16S rRNA sequencing, and groups were compared based on alpha- and beta-diversity metrics as well as differentially abundant species and genera. Results: A transdiagnostic decrease in alpha diversity and differences in beta diversity indices were observed in psychiatric patients, compared to controls. Correlation analysis of diversity metrics and PSQI score showed no significance in the patient and control groups. However, three species, Ellagibacter isourolithinifaciens, Senegalimassilia faecalis and uncultured Blautia sp. and two genera, Senegalimassilia and uncultured Muribaculaceae genus were differentially abundant in psychiatric patients with good sleep quality (PSQI > 8), compared to poor sleep quality patients (PSQI ≤ 8). Conclusion: In conclusion, this study raises important questions about the interconnection of the gut microbiome and sleep disturbances.