Sleep duration and risk of obesity: A genome and epidemiological study

Obesity is one of the risk factors for metabolic and cardiovascular diseases. Although numerous epidemiological studies have reported a possible causal association between sleep duration and the risk of obesity, evidence for an associa‐ tion in adults remains unclear. Accordingly, the present study aimed to evaluate the association between sleep duration and the risk of obesity in an adult group. To this end, 5,719 adults (2,876 males and 2,843 females) who participated in a genome and epidemiology study, were analyzed. Data were obtained on sleep duration, body mass index (BMI) and other demographic data including age, sex, waist circumference, alcohol consumption and smoking status. The association between sleep duration and obesity was investigated using a Chi‐squared test or logistic regression analysis. Multivariate logistic regression analysis revealed that a short sleep duration (≤6 h) was significantly associated with obesity after adjus‐ ting for various confounding factors (OR, 1.446; 95% CI, 1.254‐1.667; P<0.0001). Strong associations between a short sleep duration (≤6 h) and obesity were identified in males (OR, 1.567; 95% CI, 1.258‐1.953; P<0.0001) and the early midlife group (OR, 1.584; 95% CI, 1.320‐1.902; P<0.0001). Furthermore, the risk of obesity significantly increased with a short sleep duration (≤6 h) in participants without hyperten‐ sion (OR, 1.534; 95% CI, 1.263‐1.863; P<0.0001) or diabetes (OR, 1.473; 95% CI, 1.272‐1.705; P<0.0001). A short sleep duration was positively related to a high prevalence of obesity, and this association varied with sex, age, and the presence of metabolic disease. On the whole, the findings of the present study provide evidence that sleep duration can affect obesity. Introduction Obesity is a major public health concern worldwide and is related to a number of health consequences, including hyper‐ tension, diabetes mellitus, dyslipidemia, cardiovascular disease and cancer (1,2). Obesity rates have markedly increased in recent years. The number of obese individuals worldwide was estimated at 500 million in 2005, and this number is expected to increase steadily to approximately 1.1 billion by 2030 (3). The prevalence of obesity among the Korean population has also been reported to have increased from 27% in 1998 to 32% in 2011 (4). Consequently, changing one's lifestyle factors is crucial to preventing or reducing the burden of obesity. Disorders of sleep, an essential component of lifestyle, are associated with metabolic dysfunctions, which can lead to the progression of obesity (5). To date, studies have largely suggested that several hormones are involved in the regulation that occurs between sleep and body mass index (BMI) (6‐8). Some researchers have also observed that sleep restriction increased food intake and that poor sleep could exert negative effects on maintaining nervous, endocrine and cardiovas‐ cular health (9). Moreover, recent epidemiological surveys have investigated the association between sleep time and the prevalence of obesity (10‐12) as the hours of sleep represent the most essential measure of sleep. However, the overall findings remain unclear, as studies have shown associations that presented as an inverted bell‐shaped (13), were negatively linear (14‐16), or exhibited no correlation (17). Furthermore, these previous studies were mostly conducted in the United States (18), Europe (19), China (11,20) and Japan (21,22), with few studies conducted in Korea (23). Therefore, using the Korean Genome and Epidemiology Study (KoGES) data, the present study examined the associa‐ tion between sleep duration and the probability of obesity in Korean adults and investigated age‐ and sex‐specific differ‐ ences. In addition, at the reference time point, the effects of sleep on the risk of obesity were investigated, depending upon whether the participants had hypertension or diabetes. Patients and methods Study participants and design. The study dataset was obtained from the KoGES. The KoGES is an ongoing prospective cohort study that was initiated in 2001 to assess the risk and Sleep duration and risk of obesity: A genome and epidemiological study HYE OK KIM1, INSUG KANG1, WONCHAE CHOE1 and KYUNG‐SIK YOON1,2 1Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University; 2Medical Science Research Institute, Kyung Hee University Medical Center, Seoul 02447, Republic of Korea Received November 5, 2020; Accepted February 4, 2021 DOI: 10.3892/wasj.2021. 91 Correspondence to: Professor Kyung‐Sik Yoon, Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, 26 Kyungheedae‐ro, Dongdaemun‐gu, Seoul 02447,