Sleep-related daytime consequences mediated the neuroticism–depression link

Neuroticism has been found to predispose individuals to depression, but the underlying mechanism is not well studied. The current study sought to delineate the potential mediating role of sleep quality and chronotype in the relationship between neuroticism and depressive symptoms. One hundred and sixty-six Chinese youths (age: 17–24, 33.7 % male) completed measures of neuroticism, sleep quality, chronotype and depressive symptoms. Results showed that poorer sleep quality was correlated with neuroticism and depressive symptoms. Lower chronotype score (eveningness) was correlated with more depressive symptoms. Aspects of sleep quality and chronotype, namely daytime dysfunction and alertness level after waking up, were found to partially mediate the relationship between neuroticism and depressive symptoms. Results highlighted the potential roles of sleep and circadian factors concerning daytime consequences in understanding the pathology underlying the neuroticism–depression link. This study also laid the foundation for explorations on the causal relationship among these factors by further intervention and longitudinal studies. Copyright © 2016 Japanese Society of Sleep Research.