<p>This cross-sectional study examined the relationship between short sleep duration and obesity by analysing data from 3,950 participants aged 40–69 years who took part in the 2003–2004 follow-up survey of the Korean Genome and Epidemiologic Study. Based on the subjective experience of morning fatigue, short sleep duration was defined as &lt; 5&#xa0;h of sleep. Short sleep duration was significantly associated with general obesity, as measured by body mass index (adjusted odds ratios [confidence intervals], 1.246 [1.016–1.529]); these associations became stronger as the severity of general obesity worsened. Analysing data separately by sex, we detected a relationship between short sleep duration and general obesity in females only. Considering the impact of age, the relationship was detected only in females aged 40–59 years old. In females aged 40–59 years, both general obesity (1.518 [1.110–2.075]) and neck obesity (1.425 [1.045–1.945]) were associated with short sleep duration. Our study established a correlation between short sleep duration and general obesity, specifically in females and those aged 40–59 years. This finding highlights the importance of adequate sleep to treat and prevent obesity in this demographic group.</p>