Just as the title says. I worked in at least 2 safety sensitive positions. Currently a manufacturing technician at a Pharmaceutical plant and was previously hole watching in confined spaces in a cement plant. These workers are expected to work rotating shifts, nights, weekends, etc. When they are tired and overworked, that's how mistakes are made. There's all sorts of stress. Eagerness to go home, worrying about being in shape for the next day and so on and so forth. When they are dealing with heavy machinery, how are they expected to run operations smoothly? It doesn't make sense to overwork these people. In pharmas, high product quality is obviously expected. It's quite difficult to achieve this when exhausted.