Associations between personality traits and depressive symptoms vary by sleep quality among Chinese adolescents: a large cross-sectional study

Depression is prevalent in adolescents, and personality traits are important correlates of depressive symptoms. Whether the cross-sectional associations between personality traits and depressive symptoms differ according to sleep quality, gender, and grade remains unclear. This study examined the associations of the Big Five personality traits with depressive symptoms among Chinese adolescents and assessed whether these associations varied according to sleep quality, gender, and grade. A comprehensive survey was conducted in northwestern China, involving 20,320 students. Multivariable linear regression models were used to examine the associations between the Big Five personality traits and depressive symptoms. Interaction terms between sleep quality and each personality trait were used to assess whether the estimated associations varied across levels of sleep quality. The primary models adjusted for sociodemographic, family-related, behavioral, and health-related covariates. Sensitivity analyses additionally adjusted for social support, teacher–student relationship, and peer relationship. Stratified analyses examined gender and grade-level subgroups. In the primary model including all five personality traits simultaneously, Neuroticism was positively associated with depressive symptoms, whereas Conscientiousness, Agreeableness, Openness, and Extraversion were negatively associated with depressive symptoms. After additional adjustment for social support, teacher–student relationship, and peer relationship, the associations involving Agreeableness and Openness were attenuated and were no longer statistically significant. Significant statistical interactions with sleep quality were observed for Neuroticism, Conscientiousness, Agreeableness, and Extraversion, whereas the interaction involving Openness was not significant. The pattern of interaction results remained unchanged in the sensitivity analysis. Neuroticism was positively associated with depressive symptoms among Chinese adolescents, whereas Conscientiousness and Extraversion showed relatively robust negative associations. The associations involving Agreeableness and Openness were sensitive to additional adjustment for psychosocial support and interpersonal relationship factors. Significant statistical interactions indicated that the cross-sectional associations of Neuroticism, Conscientiousness, Agreeableness, and Extraversion with depressive symptoms differed according to sleep quality. These findings are associative and do not establish temporal or causal relationships.