Ongoing smartphone use links to heightened technostress. However, the content types of smartphone use are various, and little is known about which types of content use are significantly associated with technostress. This study aims to examine the impacts of specific types of smartphone use (i.e., learning-related use, entertainment-related use, social networking sites (SNS) use, and game use) on university students' technostress, and looks further into the relationship between technostress and sleep difficulty. Empirical data was collected from 512 university students studying at two Chinese public universities and analysed using structural equation modeling. Results revealed that both SNS and game use are positively associated with technostress. Both of the relationships mentioned above are significantly influenced by gender, specifically, female students are likely to experience a higher level of technostress than male students. The use of smartphones for learning and entertainment does not contribute to technostress. In addition, technostress positively predicts students' sleep difficulty. The nuanced findings of this study have practical implications for educators to intervene in university students' smartphone use.