Abstract:  Mobile phones have integrated into people’s daily lives. Proper mobile phone use would help individuals meet diverse needs in learning and shopping, as well as in recreation and communication. However, the problem that more and more people are getting addicted to mobile phones has been salient. Studies have revealed that mobile phone addiction would bring about significant adverse impacts on mental health such as depression, anxiety, and even suicidal ideation. Poor sleep quality is also one of the major undesirable outcomes of mobile phone addiction. Research documented that mobile phone addiction significantly predicted sleep quality, and sleep quality deteriorated with increasing level of mobile phone addiction. Prior studies have focused mainly on the direct association between mobile phone addiction and sleep quality, however, little is known about the underlying mediating mechanism (i.e. how mobile phone addiction influences sleep quality) and moderating mechanism (i.e. when mobile phone addiction influences sleep quality). To address these gaps, the present study constructed a moderated mediation model to examine the effect of mobile phone addiction on sleep quality in adolescents since both the use rate of mobile phone and the occurrence rate of mobile phone addiction are very high among adolescents. Specifically, the present study would examine the mediating role of affect balance in the relation between mobile phone addiction and sleep quality of adolescents, and test whether the direct effect and the indirect effect would be moderated by rumination and mindfulness. A sample of 1258 high school students completed a battery of self-report questionnaires measuring their mobile phone addiction, sleep quality, affect balance, rumination and mindfulness. All the measures showed good reliability and validity in the present study. Data were analyzed using SPSS 17.0 and the SPSS macro PROCESS which was specifically developed for assessing the complex models including both mediators and moderators. The results were as followings: (1) After controlling for gender and grade, mobile phone addiction significantly exerted direct effect on sleep quality and indirect effect on sleep quality through the mediation of affect balance. (2) Both the direct effect of mobile phone addiction on sleep quality and the indirect effect of affect balance were moderated by rumination, and these two effects were stronger in adolescents with high level of rumination. (3) Both the direct effect and the indirect effect of were moderated by mindfulness, and these two effects were weaker in adolescents with high level of mindfulness. The present study highlights the mediating role of affect balance and the moderating role of rumination and mindfulness in the effect of mobile phone addiction on sleep quality. It may contribute to a better understanding of the effects as well as its paths and conditions of mobile phone addiction on sleep quality of adolescents. Moreover, it can also provide constructive suggestions for protecting and improving affect balance and sleep quality of adolescents in the mobile Internet era.

Key words: mobile phone addiction, sleep quality, affect balance, rumination, mindfulness, adolescents