This is a meta-analysis of the pooled prevalence of sleep disturbances and its associated factors in Chinese university students. English (PubMed, PsycINFO, Embase) and Chinese (SinoMed, Wan Fang Database and Chinese National Knowledge Infrastructure) databases were systematically and independently searched from inception until 16 August 2016. The prevalence of sleep disturbances was pooled using random-effects model. Altogether 76 studies involving 112 939 university students were included. The overall pooled prevalence of sleep disturbances was 25.7% (95% CI: 22.5-28.9%). When using the screening scales Pittsburgh Sleep Quality Index, Athens Insomnia Scale and Self-Rating Sleeping State Scale, and the diagnostic criteria of the Chinese Classification of Mental Disorders (Second Edition), the pooled prevalence of sleep disturbances was 24.1% (95% CI: 21.0-27.5%) and 18.1% (95% CI: 16.4-20.0%), respectively. The percentages of students dissatisfied with sleep quality and those suffering from insomnia symptoms were 20.3% (95% CI: 13.0-30.3%) and 23.6% (95% CI: 18.9-29.0%), respectively. Subgroup analyses revealed that medical students were more vulnerable to sleep disturbances than other student groups. There was no significant difference between males and females, and across geographic locations. Sleep disturbances are common in Chinese university students. Appropriate strategies for prevention and treatment of sleep disturbances in this population need greater attention.

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Purpose The purpose of this paper is to examine how team social media usage (SMU) affects two types of knowledge sharing (KS), namely, in-role and extra-role KS, and then individual job performance. The study also examines the mediating effects of two types of KS and the main and moderating effects of team performance norms on individual job performance. Design/methodology/approach This study applies the theory of communication visibility to develop a cross-level model and then validate it through a three-wave survey from 600 individuals in 120 teams. Hierarchical linear model is used to test the hypotheses. Findings The results suggest that team SMU improves team members’ in-role and extra-role KS, and thus enhances their individual job performance. The in-role and extra-role KS have partial mediating effects between team SMU and job performance. The results also show that team performance norms have a positive main effect on individual job performance, but negatively moderate the relationship between individual extra-role KS and job performance. Research limitations/implications This study contributes to the operations management literature by examining the effects of team SMU from a multilevel perspective. Practical implications The findings provide managers with ways to improve individual KS and job performance. Originality/value This study is one of the first to investigate the effects of team SMU on individual KS and job performance. It also identifies the two-sided effects of team performance norms.