Negative life events and depression: a moderated mediation model of mobile phone addiction and chronotype among medical undergraduate students in North China.

OBJECTIVE: Although negative life events (NLEs) are known to be associated with depression, few studies have examined the potential mechanisms among medical undergraduates. In this exploratory study, we aimed to investigate relationships between NLEs and depression with the indirect effect of mobile phone addiction and the moderating effect of chronotype in a sample of medical undergraduate students in north China. METHODS: This study was a cross-sectional survey using stratified random sampling method. A total of 1,616 students in a medical college in north China was randomly chosen. Participants were asked to complete four self-reported questionnaires on an online platform, including the Patient Health Questionnaire-9 (PHQ-9), the Morning and Evening Questionnaire-5 (MEQ-5), a self-designed scale about negative life events (NLEs) and mobile phone addiction. RESULTS: This study indicated that, among the different dimensions of NLEs, study pressure, relationship setbacks and employment pressure significantly related to depression (P < 0.001). Furthermore, NLEs showed a significant indirect association with depression via mobile phone addiction. Additionally, chronotype significantly moderated the indirect effect (P < 0.001). CONCLUSIONS: Among medical undergraduates in north China, the association between NLEs and depression was indirectly associated with mobile phone addiction and moderated by chronotype, with a stronger indirect association observed in evening-type than morning-type individuals. Mobile phone addiction mediated and chronotype moderated the relationship between NLEs and depression. Morning chronotype can buffer depression with mobile phone addiction among Chinese medical undergraduate students, while evening chronotype can increase depression.