The relationship among college students’ mobile phone addiction, bedtime procrastination, and physical activity: a cross-lagged study

Aim In Chinese universities, mobile phone addiction (MPA) and bedtime procrastination (BP) are common and associated with adverse outcomes, whereas physical activity (PA) reliably benefits mental and physical health. Nevertheless, their longitudinal interplay remains underexplored. Accordingly, grounded in self-regulation theory, this longitudinal study examined the dynamic associations and potential causal pathways among MPA, BP, and PA in university students, in order to inform theory and guide future research. Methods A total of 376 university students completed a valid questionnaire on problematic MPA, BP and PA at two points in time 3 months apart. A cross-lagged model was used to examine the longitudinal relationships between these factors. Results Mobile phone addiction, BP, and PA exhibited complex temporal interrelations. Longitudinal path analyses indicated that: (1) mobile phone addiction (MPA), bedtime procrastination (BP) and physical activity (PA) all exhibited significant self-predictive effects between the two time points (MPA: β = 0.33, p < 0.05; BP: β = 0.28, p < 0.05; PA: β = 0.26, p < 0.01), indicating that these behavioral patterns exhibit a degree of stability; (2) There was a bidirectional reinforcement between MPA and BP, such that T1 MPA positively predicted T2 BP ( β = 0.24, p < 0.001) and, reciprocally, T1 BP positively predicted T2 MPA ( β = 0.20, p < 0.001); (3) PA functioned as a protective factor, whereby T1 PA predicted lower T2 MPA ( β = −0.17, p < 0.001) and lower T2 BP ( β = −0.19, p < 0.001); (4) Both MPA and BP exerted suppressive effects on PA, as T1 MPA ( β = −0.25, p < 0.001) and T1 BP ( β = −0.11, p < 0.001) negatively predicted T2 participation in PA. Conclusion The findings suggest MPA intensifies BP and reduces PA engagement, potentially creating a self-perpetuating cycle. Therefore, promoting PA may counter both MPA and BP, providing empirical support for targeted university interventions on students’ phone use and sleep behaviors.