Associations between psychological resilience and slow wave sleep in healthy adults

Abstract Introduction Psychological resilience can be viewed as a personality trait, an ability to bounce back, or a positive outcome after life adversities. Although there have been increasing reports of the importance of sleep and circadian factors in contributing to an individual’s resilience, current studies were devoid of objective measurements and in-depth analysis. Whether psychological resilience is related to the slow wave sleep that facilitates recovery processes is of particular interest. Methods This study focused on the association between resilience and sleep in healthy young individuals free of physical and mental disorders. 160 young adults (61.7% female, mean age: 29.55±4.94) were included. Psychological resilience was defined as both a trait and a positive health outcome despite adversities. The trait resilience was measured by the Connor-Davidson Resilience Scale (CDRS-10), at which scores exceeding the 50th percentile of CDRS-10 were categorized as a “High resilient trait”. The outcome resilience was measured by the residual score of the linear regression model with psychological health level as the dependent variable and accumulative adversities as the independent variable. Those with a positive residual value were categorized as “Resilient outcome”. The accumulative adversities included childhood adversities (e.g., emotional and physical neglect, sexual abuse) and lifetime stressors (e.g., accident, death of families or close friends). Sleep architecture was assessed by polysomnography, and sleep microstructure was computed by spectrum power analysis and slow wave sleep autodetection. Results Resilient participants had more slow wave sleep (SWS; N3%: 15.69% vs 12.89%, p = 0.021) and higher delta power in N3 (Absolute: 750.36 uV2 vs 617.55 uV2, p = 0.059) than those non-resilient participants. Linear regression models showed that increased SWS was associated with higher resilient trait (SWS density: B=0.25, p=0.006; Absolute power of N3 delta: B=0.003, p=0.004) and resilient outcome (N3%: B=0.02, p=0.058; SWS density: B: 0.03, p=0.073; Delta power in N3: B=0.0004, p=0.020). Conclusion Psychological resilience was related to greater slow wave sleep. The findings suggested a critical role of sleep quality in maintaining psychological resilience. Longitudinal studies are need to examine the underlying mechanism of the link between resilience and slow wave sleep. Support (if any) The Collaborative Research Fund of Hong Kong, China (C7069-19GF).