OBJECTIVES: To identify the sleep duration associated with the lowest cardiometabolic risk score in adults and to determine if the association varies by subgroups (eg, sex, age groups, ethnicity, and smoking status). DESIGN: Cross-sectional data from the 2005-2012 National Health and Nutrition Examination Survey. SETTING: Non-institutionalized civil sample from the United States. PARTICIPANTS: Age ≥20 y (N=8827) with sleep and cardiometabolic health data. INTERVENTIONS: N/A. MEASUREMENTS: Sleep duration from the Sleep Disorders Questionnaire was categorized as ≤3, 4, 5, 6, 7, 8, 9, and ≥10 h per night. HDL cholesterol (HDL) and waist circumference (WC) were stratified by sex first, while fasting insulin, fasting plasma glucose (Glu), triglycerides (TG), body max index (BMI), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were standardized without stratifications. The standardized scores were summed for each participant using the following formula: -zHDL + zInsulin + zGlu + zTG + (zBMI + zWC)/2+(zSBP + zDBP)/2. RESULTS: Seven hours of sleep was associated with the lowest cardiometabolic risk score (-0.30 (95% CI: -0.43, -0.18)), which remained similar after adjusting for age, sex, ethnicity, education, family income, alcohol intake and smoking status. However, 8 hours of sleep was associated with the lowest score in non-Hispanic Blacks. CONCLUSIONS: This study supports recent sleep duration recommendations in adults, and provides evidence that in general 7 hours of sleep per night is associated with optimal cardiometabolic health of adults. Longitudinal studies using objective measures of sleep would help further clarify this association.