Background <p>University students experience insomnia at rates higher than those of other age groups, creating significant challenges to their physical and mental health, as well as their academic achievements. While recent research has highlighted the potential of mindfulness to improve sleep quality, the mechanisms through which mindfulness alleviates insomnia remained understudied. Pain catastrophizing has been identified as a mediating factor in this relationship, but the role of positive mental states, such as gratitude, has received limited attention. Drawing on Dual Processing Theory, Mindfulness-to-Meaning Theory, and Broaden-and-Build Theory, this study examines how negative cognitive processes like pain catastrophizing and positive traits like gratitude influence the connection between mindfulness and insomnia.</p> Methods <p>A cross-sectional survey was conducted among university students from a higher education institution in Southwest China. Participants completed a set of well-established and validated self-report instruments, including the Mindful Attention Awareness Scale (MAAS), the Athens Insomnia Scale (AIS), the Pain Catastrophizing Scale (PCS), and the Gratitude Questionnaire-6 (GQ-6), along with demographic questions. Structural equation modeling (SEM) was employed to examine the hypothesized structural relationships among trait mindfulness, pain catastrophizing, gratitude, and insomnia.</p> Results <p>A total of 1,361 valid responses were included in the analysis. The findings revealed that trait mindfulness significantly mitigated insomnia, which is consistent with the existing literature. Additionally, mindfulness improved sleep quality by reducing negative cognitive processes associated with pain catastrophizing and enhancing gratitude.</p> Conclusions <p>This study offers valuable theoretical and empirical insights that may inform approaches to enhancing sleep quality through trait mindfulness-related cognitive pathways.</p>