Sleep deficiency is becoming widespread in both adults and adolescents and is accompanied by certain behaviors that can lead to obesity. This study aims to investigate differences in sleep duration of overweight/obese and normal weight groups, and the association between sleep deprivation and obesity, dietary intake and physical activity. A cross-sectional study was conducted among 226 Iranian working adults (109 men and 117 women) aged 20 to 55 years old who live in Tehran. Body weight, height, waist and hip circumferences were measured, and BMI was calculated. Questionnaires, including the Sleep Habit Heart Questionnaire (SHHQ), International Physical Activity Questionnaire (IPAQ) and 24-hour dietary recall, were interview-administered. Subjects were categorized as normal weight (36.3%) The findings in this study confirm that people with shorter sleep duration are more likely to be overweight or obese; hence, strategies for the management of obesity should incorporate a consideration of sleep patterns.