Longitudinal association between social media exposure and nonsuicidal self-injury among adolescents: investigating the directionality by within-person effects

Social media is increasingly popular among adolescents, and it has been integrated into their daily life. Previous research have indicated mix results in the relationship between social media exposure and nonsuicidal self-injury (NSSI) behaviors. Given that most of prior studies were cross-sectional, the present study investigated the reciprocal relation between exposure to NSSI on social media and NSSI behaviors using longitudinal data among Chinese adolescents. We conducted three waves assessment among 1962 secondary school adolescents (52.3% females; M age = 14.59 years, SD age = 1.27), with a six-month interval between each wave (Wave 1: November 2020; Wave 2: May 2021; Wave 3: November 2021). Social media exposure to NSSI, actual NSSI engagement, and depression were assessed at each wave by self-report questionnaires. Consistent with our hypotheses, social media exposure, NSSI, and depression were significantly and positively related to each other across all waves. Results showed a bidirectional association between social media exposure and NSSI, even after controlling for depression. Greater exposure to NSSI on social media predicted more frequently engagement in NSSI over time, and vice versa. Findings of this study suggest a bidirectional association between social media exposure and NSSI among adolescents. Interventions that encourage media education may decrease the media’s influence on the contagion of NSSI.