Situation awareness is an important factor in the incidence of industrial accidents. Improving situation awareness may help to prevent occupational accidents. Determination of factors influencing the situation awareness will help to plan and implement the measures for improving working conditions and making a safer workplace. In this study, was examined the role of work overload and sleepiness in predicting work situation awareness among workers. It was a cross-sectional study. The sample consisting of 180 employees at a petrochemical industry was selected according to the random stratified sampling method. They were asked to respond to questionnaires including work situation awareness of Sneddon, Mearns & Flin, work overload of Beehr, Walsh & Taber, and Epworth sleepiness scale. The results showed that there was an internal correlation among work overload, sleepiness, and work situation awareness. Also, the results of stepwise regression analysis revealed that work overload and sleepiness significantly predicted, respectively, almost 10% and 24% of variances of work situation awareness among the workers. Thus, for improving workplace safety, interventional measures can focus on enhancing situation awareness via workload and sleepiness reduction.