The Association Between Physical Exercise and Sleep Quality Among Junior Middle School Students: The Mediating Role of Social Support and the Moderating Role of Mindfulness.

This study explores the relationship between physical exercise and sleep quality, focusing on the mediating role of social support and the moderating role of mindfulness. The sample included 1,023 junior middle school students (51.22% females; mean age = 13.59 ± 0.84 years). Participants completed measures of physical exercise, sleep quality, social support, and mindfulness. Data were analyzed using descriptive statistics, bias-corrected bootstrap procedures, and Hayes' PROCESS macro for SPSS (Models 4 and 59). The results showed that 24.73% of the participants screened positive for sleep problems (Pittsburgh Sleep Quality Index (PSQI) > 7), and physical exercise was significantly positively associated with sleep quality. Social support played a significant mediating role in the relationship between physical exercise and sleep quality. Mindfulness significantly moderated the association between social support and sleep quality and the residual direct association between physical exercise and sleep quality, but did not significantly moderate the association between physical exercise and social support. At higher levels of mindfulness, the positive associations of physical exercise and social support with sleep quality were stronger. These findings revealed the roles of social support and mindfulness in the association between physical exercise and sleep quality and provided a new perspective for sleep-health promotion among junior middle school students. Schools, families, and communities should coordinate efforts to promote physical exercise, strengthen social support, and cultivate mindfulness among junior middle school students.