Results
Smartphone addiction was positively associated with sleep quality (β = 0.066, 95% CI [0.048,0.084], p < 0.001), negatively associated with physical learning engagement (β=-0.107, 95% CI [-0.203,-0.010], p = 0.031), and positively associated with self-esteem (β = 0.072, 95% CI [0.038,0.106], p < 0.001). Sleep quality was positively associated with self-esteem (β = 0.402, 95% CI [0.248,0.557], p < 0.001). Notably, the positive associations involving self-esteem were directionally inconsistent with most prior literature and should be regarded as unexpected and exploratory. The indirect effect through sleep quality was significant for both female students (effect=0.026, 95% CI [0.014,0.042]) and male students (effect=0.018, 95% CI [0.008,0.029]), whereas the indirect effect (effect=0.007, 95% CI [0.002,0.014]) through physical learning engagement and the serial indirect effect (effect=0.002, 95% CI [0.001,0.005]) were significant only among male students. However, none of the indices of moderated mediation was significant. Gender significantly moderated the direct smartphone addiction-self-esteem association (β=-0.055, 95% CI [-0.101,-0.010], p = 0.017). In addition, LPA identified three distinct subgroups characterized by different combinations of sleep quality and physical learning engagement, and these subgroups differed significantly in smartphone addiction and self-esteem.
