BACKGROUND: Social media use and daytime sleepiness are common among university students and have significant implications for their mental health. The aim of this study was to examine the effects of social media use on suicidal ideation among university students and to analyse the mediating effects of daytime sleepiness and sleep quality. METHODS: A total of 5899 full-time undergraduate students were included in this study. Questionnaires were distributed and collected using the QuestionStar platform. Logistic regression analysis was used to examine the association between social media use, daytime sleepiness and sleep quality, and suicidal ideation among college students. The mediation model was tested using the bias-corrected percentile bootstrap method. RESULTS: Among 4835 students, 612 (12.66 %) reported having had suicidal ideation. Regression analysis revealed that social media use (OR = 1.09, 1.05-1.12), daytime sleepiness (OR = 1.09, 1.06-1.11), general and poor sleep quality (OR = 1.89, 1.56-2.28
OR = 4.82, 3.76-6.18) were all significantly and positively associated with suicidal ideation. Furthermore, there was a chain-mediated effect of daytime sleepiness and sleep quality on the relationship between social media use and suicidal ideation. LIMITATIONS: Causality could not be explored by cross-sectional studies, and future cohort studies are needed. CONCLUSIONS: There was a chain-mediated effect between daytime sleepiness and sleep quality in the relationship between social media use and suicidal ideation. Therefore, it is recommended that students reduce their use of social media to improve their sleep quality and mental health.