Background Emotional eating is a prevalent maladaptive coping mechanism among college students, which is associated with mental health and sleep concerns. Though previous studies have established a link between sleep quality, depression and emotional eating, most of these have been in Western populations. In addition, few existing studies have taken physical activities into account, and the underlying mechanisms between these four variables remain to be further studied. Therefore, our study investigated the mediating role of depression and the moderating role of physical activity levels in the relationship between sleep quality and emotional eating among Chinese college students. Our study can help to understand the characteristics of this population and provide guidance on the intervention pathways for emotional eating. Methods A convenience sampling method was employed to select eligible participants for investigation. The General Information Questionnaire, the Pittsburgh Sleep Quality Index Scale, the Patient Health Questionnaire, the Dutch Eating Behavior Scale, and the International Physical Activity Questionnaire were employed to measure the general condition, sleep quality, depression, emotional eating, and physical activity. A total of 813 college students (M-age = 19.14, SD = 1.12, range = 17 similar to 25 years old, 71.1% females) completed the survey. The moderated mediation analysis was carried out using the SPSS PROCESS macro. Results After controlling for sex, age, and body mass index (BMI), sleep quality positively predicted emotional eating. Depression primarily mediated the association between them. Besides, physical activity levels moderated the relationship between sleep quality and emotional eating via depression. Depression significantly predicted emotional eating among students with low levels of physical activity; however, it was not significant among students with moderate or high levels of physical activity. Conclusions The role of depression mediates the link between sleep quality and emotional eating. Regular exercise can ease the symptoms of emotional eating through depression. This implies the importance of offering more sleep hygiene education and physical activity in university settings. College students often experience poor sleep quality and negative emotions due to different kinds of pressure, which can lead to emotional eating. But the mediating or moderating mechanism is not fully understood between them. Our research looked at how depression might explain this connection and whether physical activity can help. We surveyed 813 college students about their sleep quality, depression, emotional eating, and physical activity levels. The results showed that students with poor sleep were more likely to eat emotionally, which was totally mediated by depression. However, students who were physically active were less affected by this pattern. This means that regular exercise can weaken the impact of poor sleep and depression on emotional eating. Our findings suggest that encouraging good sleep habits and physical activity in colleges can help prevent emotional eating.
