The dynamic interplay of cyberbullying victimization and self-injury: a longitudinal investigation of rumination and friendship quality in Chinese vocational students

This longitudinal study examined the relationship between cyberbullying victimization (CV) and non-suicidal self-injury (NSSI) among Chinese vocational college students, testing the mediating role of ruminative contemplation (RC) and the moderating effect of friendship quality (FQ). A six-month longitudinal design was implemented with 2,312 vocational students (Mage(T1) = 19.06; 35.55% CV prevalence, 19.26% NSSI prevalence at baseline). Data were collected at two waves (T1: December 2024; T2: June 2025) using validated scales: Cyberbullying Inventory for College Students (CICS), Adolescent Self-Harm Questionnaire, Event-Related Rumination Inventory (C-ERRI), and Friendship Quality Questionnaire (FQQ-C). Cross-lagged panel models (CLPM) and moderated mediation analyses were conducted via Mplus 8.3, controlling for gender, only-child status, and residence. CV directly predicted increased NSSI over time. RC mediated the CV→NSSI link. FQ significantly buffered the direct CV→NSSI pathway, with maximal protection observed at FQ scores = 212.3 (Johnson-Neyman analysis). Cyberbullying victimization heightens NSSI risk both directly and indirectly through ruminative contemplation. High-quality friendships mitigate this pathway, offering a critical protective factor for vocational students. Interventions should target RC reduction and FQ enhancement to disrupt the CV→NSSI trajectory.