Peer Victimization and Non-Suicidal Self-Injury Among Chinese Adolescents: Moderating Roles of Teacher Emotional Support and Parent–Child Cohesion

Non-suicidal self-injury (NSSI) is a highly prevalent maladaptive psychological behavior among adolescents and a significant public health concern. Drawing upon ecological systems theory, this cross-sectional study of 4128 adolescents (M = 12.78, SD = 0.96; 51.6% male) aimed to investigate the underlying mechanisms and protective roles of peer victimization, sleep quality, parent–child cohesion, and teacher emotional support in relation to NSSI. Hierarchical regression analyses and PROCESS macro were used to test the proposed mediating and moderating effects. Peer victimization was significantly correlated with NSSI, and this relationship was mediated by sleep quality. In separate models, the interaction terms of peer victimization × parent–child cohesion, sleep quality × parent–child cohesion, and sleep quality × teacher emotional support were each significantly associated with NSSI. However, when both moderators were examined simultaneously, only teacher emotional support remained a significant moderator of the sleep quality–NSSI pathway. These findings highlight the complex pathways linking peer victimization to NSSI, clarify the differentiated moderating roles of family and school support, and provide empirical support for ecological systems theory and school-based interventions.