The dynamic relationship between social media use and interpersonal adaptation among freshmen in their first month of college: A moderated intensive longitudinal mediation model

College freshmen face the critical challenges of reconstructing their social networks and adapting interpersonally during the early college entry period. Whether social media facilitates freshmen's relational integration or induces interpersonal alienation remains debated, and the underlying mechanisms and boundary conditions require clarification. In this study, 306 freshmen completed a 30-day intensive longitudinal survey during their first month of college. Using residual dynamic structural equation modeling (RDSEM), we examined the microtemporal association between social media use and interpersonal adaptation, the intensive mediating role of self-concept clarity, and the cross-level moderating effect of envy. The results showed that: (1) social media use on the previous day significantly and negatively predicted freshmen's interpersonal adaptation on the current day; (2) social media use on the previous day indirectly and negatively affected freshmen's interpersonal adaptation on the next day by reducing self-concept clarity on the current day; and (3) envy exerted a cross-level moderating effect, such that freshmen with higher envy were more likely to show reduced self-concept clarity on the current day and poorer interpersonal adaptation on the next day after using more social media on the previous day. These findings deepen understanding of the mechanisms through which social media negatively affects college adjustment and provide practical implications for helping freshmen adapt smoothly to college in the contemporary digital ecology.