Abstract
<title>Abstract</title> <p> <bold>Background</bold> The incidence of non-suicidal self-injury (NSSI) behaviors among middle school students has been continuously rising, yet its underlying influencing factors and intrinsic mechanisms remain to be further clarified. This study aims to investigate the longitudinal impact of family sports behavior environment (FSBE) on NSSI among middle school students, with a focus on exploring the mediating role of short video addiction (SVA) and depression (DEP) in this process. <bold>Methods</bold> A convenient sampling method was adopted to recruit 968 middle school students as participants. Questionnaire surveys were administered at two time points with a 6-month interval using the Family Sports Behavior Environment Scale, Short Video Addiction Scale, Center for Epidemiologic Studies Depression Scale, and Non-Suicidal Self-Injury Assessment Questionnaire. All data were processed and analyzed using SPSS and AMOS statistical software. <bold>Results</bold> (1) FSBE at T1 was significantly negatively correlated with SVA, DEP and NSSI at both T1 and T2. Besides, SVA, DEP and NSSI presented significant positive correlations between T1 and T2. (2) In the cross-sectional baseline model (T1), the chain mediating effect of SVA and DEP was statistically significant, with a total indirect effect value of − 0.191, accounting for 45% of the total effect, and all three indirect pathways were significant.(3) In the longitudinal follow-up model (T1→T2), the chain mediating effect remained robustly significant, with a total indirect effect value of − 0.129, accounting for 41% of the total effect. Compared with the baseline model, the longitudinal mediating effect value and its proportion in the total effect decreased slightly, but the effect remained highly significant. <bold>Conclusion</bold> SVA and DEP play a chain mediating role in the relationship between FSBE and NSSI among middle school students. A positive family sports environment can alleviate short video addiction among middle school students, reduce their depressive mood, and subsequently effectively lower the risk of NSSI behavior. </p>