The purpose of this study was to examine whether social relationships were associated with sleep status in Chinese undergraduate students. A cross-sectional questionnaire survey was conducted in November 2012 at Huzhou Teachers College, China. The questionnaire involved demographic characteristics, personal lifestyle habits, social relationships and Pittsburgh Sleep Quality Index (PSQI). The associations between social relationships and sleep status were analyzed by using regression models after adjustment for potential factors. Poor sleep quality was prevalent among Chinese undergraduate students. Men tended to have better sleep than women. Lower social stress, better management of stress and good social support were correlated with better sleep status, and stress or support from friends, family and classmates were all related with sleep variables. While only weak associations between number of friends and sleep were detected. The results were consistent in men and women. Educators and instructors should be aware of the importance of social relationships as well as healthy sleep in undergraduates. (c) 2014 Elsevier Ireland Ltd. All rights reserved.