A Serial Mediation Model of the Relationship Between Rejection Sensitivity and Non-Suicidal Self-Injury Among In-School Adolescents: The Role of Bullying Victimization and Loneliness

Introduction: The relationship between rejection sensitivity and non-suicidal self-injurious (NSSI) behaviors has been documented; however, the mechanisms leading to NSSI remain unexplored. This study examined whether bullying victimization and loneliness mediate the association between rejection sensitivity and NSSI among in-school adolescents. Method: A total of 300 students (ages 13-16) from seventh to ninth grades in Birjand, Iran completed validated measures of rejection sensitivity, bullying victimization, loneliness, and NSSI. Data were analyzed using SPSS and Hayes’ PROCESS macro with 5,000 bootstrap resamples. Results: Approximately 38.7% of the participants reported experiencing victimization at least two to three times per month. The direct effect of rejection sensitivity on NSSI was not significant (β = 0.102, p > .05), whereas victimization significantly mediated this relationship (β = 0.296, p < .001). Victimization predicted loneliness (β = 0.332, p < .001), which in turn was associated with higher NSSI (β = 0.241, p < .001), revealing a full serial mediation. Conclusion: These findings suggest that adolescents high in rejection sensitivity are more likely to experience peer victimization, fostering loneliness and increasing the likelihood of engaging in NSSI. Interventions focusing on reducing bullying and enhancing socio-emotional support may help prevent self-injurious behaviors among vulnerable youth.