Obesity is a major public health burden in developed countries 1-3 and is also a well-known risk factor of cardiovascular disease (CVD). Short sleep duration is associated not only with obesity 4 , but also with diabetes mellitus 5 , heart disease 6-8 , and death. 9 An inverse relationship between inadequate sleep duration and obesity has been shown in young adults 10 , specifically in young women. 11 Associations between sleep duration and health indicators differ according to factors such as race, culture, and sex. 12 Koreans, in particular, are known to have relatively few sleep hours compared with those in other Organization for Economic Cooperation and Development (OECD) countries. 13 However, few studies have focused on the association between sleep duration and obesity in the Korean population. Therefore, we investigated the association between sleep duration and obesity after adjusting for socioeconomic position, health behaviors, and other clinical factors. Methods 1. Study population Data were collected from the 2007-2009 Korea National Health and Nutrition Examination Survey (KNHANES) conducted by the Ministry of Health and Welfare of Korea. 14 The survey applied a stratified, multistage probability sampling design to the South Korean population using a three-stage, stratified, systematic sampling method. The KNHANES included three questionnaires: a health interview survey, a health behavior survey, and a health examination. The health interview survey sample included 13,800 households and 31,705 household members from 600 districts. One of every three