Longitudinal associations between fear of missing out, problematic social media use, and problematic smartphone use

Fear of missing out (FoMO) has been linked to problematic smartphone use (PSU) and problematic social media use (PSMU), but it remains unclear whether these associations reflect stable between-person differences or dynamic within-person processes over time. To address this, we analyzed five-wave longitudinal data (N = 1,596, females = 1,055, M _age = 19.70, SD = 1.60) using Random-Intercept Cross-Lagged Panel Models (RI-CLPMs) to disentangle between- and within-person associations longitudinally. Our observations revealed that: (1) PSU and PSMU were strongly correlated across time, indicating substantial overlap between the two behaviors; (2) FoMO positively predicted both PSU and PSMU, and these behaviors also predicted higher subsequent FoMO, suggesting bidirectional relations; and (3) FoMO and PSU exhibited moderate temporal stability. These observations underscore a subtle but persistent interplay between FoMO, PSU, and PSMU over time.