Association between social media use and mental and physical health among university students in Japan.

This study investigated associations between social media use and mental and physical health among university students in Japan, integrating the dual-factor model of mental health with a portfolio-based perspective on social media. Mental health was assessed using subjective well-being (SWB) and depression tendency (DT), and physical health using gastrointestinal problems (GP) and headaches. An online survey of 462 participants identified two predominant usage patterns that were retained for subgroup analysis: LINE + X + Instagram (Group 1, n = 123) and LINE + X + Instagram + Discord (Group 2, n = 99). Across both groups, higher SWB was associated with lower DT, and GP was indirectly related to higher DT through headaches. In Group 1, adaptive interpersonal traits (e.g., higher generalized trust and social competence, and lower social anxiety) were associated with more social support, which in turn was associated with fewer GP and better mental health outcomes. However, longer time spent on LINE and Instagram was associated with increased headaches, suggesting potential physiological costs of frequent use. In Group 2, higher private self-consciousness was associated with more GP, indicating a possible vulnerability pathway. Platform-specific patterns also emerged: Instagram use was associated with higher DT, whereas X use showed mixed associations. Overall, these findings highlight the importance of considering individual differences and usage patterns, and contribute to a more nuanced understanding of how social media use is differentially associated with mental and physical health.