Driving a commercial vehicle is a physically and mentally challenging job. Long hours, customer demands, and other traffic are a lot to deal with. Driver fatigue is a constant companion to the truck driver. Mental stress; such as financial concerns, issues at home, or medical problems, can all weigh heavily on an already tired person. Please stay aware of your alert status. Drowsiness is an advanced stage of fatigue. When you are tired – STOP – REFRESH! Sleep is involuntary; you can doze of at a moments notice.