This study focuses on middle school students and analyzes the relationship between CM, EIPs, sleep quality, and psychological resilience. The descriptive analysis results indicate a significant correlation between the above variables. Intermediary analysis found that both sleep quality and psychological resilience can mediate the association between CM and EIPs independently or continuously. At the same time, the positions of the two mediating variables (sleep quality and psychological resilience) in this continuous mediation can be swapped.
Firstly, the results of the direct effect indicate a significant positive correlation between EIPs in adolescents and CM, and experiencing more CM indicates more EIPs, which is similar to the results of a recent study[47]. A reduction in the volume of the brain's hippocampus, a region with higher concentrations of glucocorticoid receptors, has been demonstrated in those who experience CM[48, 49], and glucocorticoids increase an individual's susceptibility to EIPs, such as depression, via the hypothalamic-pituitary-adrenal (HPA) axis[50, 51]. The stress model provides another explanation: exposure to early negative life events (such as CM) increases an individual's stress, while high levels of stress increase individual susceptibility to psychological and behavioral problems[52]. Some argue that CM is often associated with lower socio-economic status, and that poor parenting practices are associated with EIPs[53].
Secondly, we found that sleep quality mediates the association between CM and adolescent EIPs, which is consistent with our hypothesis. The impact of CM on sleep quality is persistent and can last up to 50 years[54, 55]. Adolescents who have experienced CM tend to choose adaptive emotional regulation strategies when faced with emotional distress[2], and they take longer to shake off the effects of negative emotions, and sleep quality during this period is significantly affected[56]. Poor sleep quality can lead to a series of EIPs such as emotional disorders and attention deficit hyperactivity disorder (ADHD)[57, 58]. The possible reason is that sleep problems lead to intermittent hypoxia, resulting in increased physical activity[58], reduced social interaction, and emotional disorders, among other psychological and behavioral problems[59].
Next, the resilience of our research center also mediates the association between CM and adolescent EIPs. Research has shown that resilience plays a protective role in the process of internalizing and externalizing issues in children who experience abuse[60], and our analysis results are similar to this. The association between CM and psychological resilience is still controversial. Yoon et al. believe that CM cannot significantly predict resilience[61], which may be related to his consideration of only a single type of abuse. Another study suggests that CM negatively predicts psychological resilience, indirectly affecting emotions[30]. As psychological problems accumulate, it ultimately leads to various EIPs such as conduct disorders and ADHD[19, 62].
Finally, we found that sleep quality and psychological resilience continuously mediate the association between CM and EIPs. CM reduces psychological resilience by reducing sleep quality, ultimately leading to EIPs. Individuals with poor sleep quality are unlikely to have better self-reported mental health status, so the evaluation results of psychological resilience are usually lower[38]. It is worth noting that after swapping the order of the two mediating variables (psychological resilience, sleep quality), the chain mediation effect (CM - psychological resilience - sleep quality - EIPs) remains significant. Similar studies claim that resilience mediates the association between family dysfunction and adolescent sleep quality, and interventions targeting resilience may improve sleep quality[63]. Low elasticity may lead to insomnia through supporting emotions and arousal disorders, which seems to be a vicious cycle: low elasticity leads to poor sleep quality, which in turn leads to low elasticity[64].
This study has the following advantages. Firstly, our data comes from a large sample size (n = 1605) cohort of junior high school students, analyzing the association between CM and EIPs in adolescents, as well as the mediating role of sleep quality and psychological resilience, which increases the reliability of the results. Secondly, we fully controlled for covariates that may be related to EIPs, and standardized the results of the mediation analysis. Thirdly, we explored the impact of the vertical order of two mediating variables on the chain mediated effect.
There are still limitations to this study: firstly, we did not use baseline data on adolescent EIPs, which may result in biased results. Secondly, this study only used the total score of CM and the total score of EIPs for analysis, without considering the individual effects of different types of CM and the impact of CM on a single internalizing/externalizing problem. Next, we will not discuss the gender differences in mediating effects. In addition, most of the research data is self-reported by students, and retrospective collection of CM data may have recall bias. Finally, this study was only conducted among middle school students, and the research findings may not be applicable to the adolescent population, including high school students.
This longitudinal study provides evidence of mediating variables in the association between CM and EIPs among adolescents. The analysis results indicate that both sleep quality and psychological resilience can independently mediate the above associations. In addition, we determined that the sequence of two mediating variables (sleep quality and psychological resilience) before and after swapping will not change the significance of the chain mediation effect. The significance of these findings is that by helping to improve the sleep quality of adolescents and enhancing their psychological resilience, it may prevent or reduce EIPs among those who have experienced CM.