肥胖的发生由环境和遗传因子共同决定。它和睡眠时间具有很强的相关性，在儿童期尤为显著。肥胖和睡眠障碍是多种疾病的共同危险因子，同时又被多种共同的危险因子影响。因此它们有着某些共同的病理机制。然而，关于睡眠对肥胖发生的作用机理仍然不清楚，相关的研究也比较缺乏。在本研究中，我们提出了一个因果作用概念模型，描述了睡眠诱导肥胖发生的3种作用机制: 睡眠对环境因子的中介作用，睡眠通过肥胖生物标志物的间接作用，以及睡眠和遗传因子的交互作用。根据这个模型，我们将在上海学龄期儿童样本中，应用流行病、统计和遗传研究方法，发现在模型中和睡眠发生作用的环境，生物标志物和基因因子，并评估睡眠介入的作用大小。本研究的结果将有助于发现和理解睡眠障碍和肥胖的发生机制，从而为儿童肥胖的早期预防，早期诊断和有效治疗提供有力的理论依据。

Obesity is caused by environment and genetic factors jointly. It has strong correlation with sleep duration, which is especially obvious in the childhood. Obesity and sleep disorder are common risk factors of many diseases, and they are also impacted by many common risk factors. Therefore, they share some common pathogenesis. However, it remains unknown how sleep influences obesity.pathogenesis, and there is a lack of relevant research. In this study, we proposed a conceptual model of causal effect that describes three types of pathogenic mechanisms induced by sleep problems: mediation effect of sleep on environment factors, indirect effect of sleep through obesity-related biomarkers, and interaction effect between sleep and genetic factors. Based on this model, we will apply epidemiology, statistic and genetic research methods in Shanghai school-aged children to discover those environment, biomarker and genetic factors involved with sleep effect and estimate the sleep effect size. We believe results of this research will contribute to discovery and understanding of sleep disorder and obesity pathogenesis, promoting early prevention, early discovery and effective treatment of childhood obesity.