Sex differences in sleep architecture among patients with severe mental disorders: a polysomnographic study.

Background: Sleep disturbances are common in severe mental illness, including schizophrenia, bipolar disorder, and major depressive disorder. Yet sex-specific sleep patterns across schizophrenia, bipolar disorder, and major depressive disorder remain poorly characterized. Methods: In this cross-sectional study, we compared overnight polysomnography between 372 first-episode patients (aged 18-45) (93 schizophrenia, 181 major depressive disorder, 98 bipolar disorder). All participants underwent a single-night 10-channel polysomnography. Results: After controlling for age, illness duration, BMI, and medications, women achieved significantly longer total sleep time (median 449.3 vs 420.3 min; p <0.001), time in bed (543.0 vs 525.5 min; p = 0.03), and higher sleep efficiency (83.3% vs 82.3%; p = 0.004) than men. Exploratory Conclusions: This study found that biological sex modulated sleep macro-architecture in severe mental illness, with women exhibiting longer sleep duration and higher sleep efficiency relative to men. Although the cross-diagnosis comparison revealed only a marginally significant sex-by-diagnosis interaction that did not persist after multiple testing correction, these exploratory subgroup findings suggest potential nuanced variations in sleep architecture. Consequently, future studies with larger cohorts are warranted to evaluate whether sex-stratified approaches could refine clinical sleep interventions across psychiatric conditions.