Relative deprivation and non-suicidal self-injury among Chinese adolescents: the mediating role of problematic mobile phone use and the moderating role of physical activity

Introduction Relative deprivation may be associated with non-suicidal self-injury (NSSI) in adolescents, but the behavioral factors underlying this association remain unclear. This study examined the indirect association between relative deprivation and NSSI through problematic mobile phone use (PMPU) and the moderating role of physical activity in this association. Methods In this cross-sectional study, 1,040 adolescents (550 boys [52.9%] and 490 girls [47.1%]; M age = 12.71, SD = 0.64) completed measures of relative deprivation, PMPU, NSSI, and physical activity. Data were analyzed using SPSS 26.0 and PROCESS Models 4 and 14, with age, sex, and parental education as covariates and cluster bootstrap resampling to account for the clustering of students within classes. Results Relative deprivation was positively associated with NSSI. This association was partly indirect through PMPU (indirect effect = 0.08, 95% CI [0.05, 0.11]), accounting for 23.9% of the total effect. Physical activity significantly moderated the association between PMPU and NSSI ( B = −0.002, p < 0.001), with a weaker positive association at higher levels of physical activity. Conclusion Relative deprivation may be indirectly associated with NSSI through PMPU, and this indirect association was weaker at higher levels of physical activity. These findings provide new evidence for understanding the behavioral factors associated with adolescent NSSI.