International Journal of Preventive Medicine (Int J Prev Med)2008-78021342022071726502650ENNutrition and Food Security Research Center & Department of Nutrition, School of Public Health, Shahid Sadoughi University of Medical Sciences, YazdYazd Cardiovascular Research Center, Shahid Sadoughi University of Medical Sciences, YazdResearch Center of Prevention and Epidemiology of Non-Communicable Disease, Department of Biostatistics and Epidemiology, School of Health, Shahid Sadoughi University of Medical Sciences, YazdNutrition and Food Security Research Center & Department of Nutrition, School of Public Health, Shahid Sadoughi University of Medical Sciences, YazdSchool of Traditional Iranian Medicine, Kerman University of Medical Sciences, KermanNutrition and Food Security Research Center & Department of Nutrition, School of Public Health, Shahid Sadoughi University of Medical Sciences, YazdNutrition and Food Security Research Center & Department of Nutrition, School of Public Health, Shahid Sadoughi University of Medical Sciences, Yazd20220716<strong>Background</strong>: Little observational studies have been conducted on the association between diet and sleep. We conducted a cross-sectional study to evaluate the associations of dietary patterns with sleep duration in an Iranian population. <strong>Methods</strong>: This study was conducted on the baseline data of two population-based Iranian cohorts: the YaHS-TAMYS and Shahedieh studies. Dietary intakes were assessed in 10451 Yazdi people aged 20–75 years. Dietary habits were derived from answers to a food frequency questionnaire, and a factor analysis using principal component analysis (PCA) was used to identify dietary patterns. The reported sleep duration was categorized as short (&lt;6 h), normal (6–8 h) or long (&gt;8 h). Multivariable logistic regression was used to determine the relationship between dietary patterns and the odds of short and long sleep duration. <strong>Results</strong>: Four major dietary patterns were identified: “healthy,” “western,” “traditional,” and “high-carbohydrate, high-fat.” In the Shahedieh study, participants in the top quartile of the western dietary pattern had greater odds of short (&lt;6 h) and long (&gt;8 h) sleep duration (OR = 1.49; 95% CI: 1.17, 1.90; P trend &lt;0.001 and OR = 1.46; 95% CI: 1.12, 1.90; P trend = 0.014, respectively) than those in the bottom quartile. Also, participants in the highest quartile of the high-carbohydrate, high-fat pattern had higher odds of long sleep duration compared with those in the lowest quartile (OR = 1.36; 95% CI: 1.05, 1.75; P trend = 0.005). Pooling the two studies revealed that the western dietary pattern was significantly associated with short sleep duration (OR = 1.31; 95% CI: 1.08, 1.59). <strong>Conclusions</strong>: The western dietary pattern might inversely be associated with sleep duration. Future prospective studies are recommended to confirm these results.http://ijpm.mui.ac.ir/index.php/ijpm/article/view/2650http://ijpm.mui.ac.ir/index.php/ijpm/article/download/2650/717718485