Course, risk factors, and mental health outcomes of excessive daytime sleepiness in rural Chinese adolescents: A one-year prospective study

Background: This study aimed to examine the one-year incidence and persistence of excessive daytime sleepiness (EDS) in rural Chinese adolescents and their risk factors. In addition, we also aimed to explore the potential bidirectional associations of EDS with anxiety symptoms and depressive symptoms. Methods: A total of 3736 adolescents from 5 high schools from rural area in the south China were eligible for follow-up. Among them, 2787 responded to follow-up after one year. EDS was defined as having a total score of the Epworth Sleepiness Scale over 10. Results: The one-year persistence rate and incidence rate of EDS were 27.6% and 9.3%, respectively. After controlling for age and sex, new incident EDS was significantly associated with perceived high study stress, depressive symptoms, insomnia symptoms, and high life events at baseline. Baseline EDS predicted new onsets of depression and anxiety at follow-up. Cross-lagged analyses further revealed that there were bidirectional associations between EDS and anxiety symptom and between EDS and depressive symptoms. Persistent EDS was only associated with eveningness chronotype. In particular, short sleep duration and obesity were associated with neither new incidence nor persistence of EDS in this population. Limitations: All measures relied on self-reported questionnaires rather than objective assessments, which might have led to report bias. Conclusions: We have identified a number of risk factors of the one-year incidence of EDS (such as perceived high study stress, depressive symptoms, insomnia symptoms, and high life events) and persistence of EDS (eveningness chronotype) in rural adolescents. There is a reciprocal relationship of EDS with anxiety and depression. In this population, sleep loss and obesity seem not related to the course of EDS.