Final answer:
Sleep deprivation in commercial vehicle drivers is often caused by long working hours and irregular schedules, leading to reduced alertness and increased accident risk.
Step-by-step explanation:
Two factors that may lead to sleep deprivation among drivers of large trucks and buses, despite their specialized training and licensing, are long working hours and irregular schedules. These conditions can contribute to accumulating a 'sleep debt', making it difficult for drivers to stay alert and increasing the risk of accidents on the road. The effects of sleep deprivation are profound, with reduction in mental alertness, cognitive function, and reflexes, which are essential for safe driving. Commercial vehicle drivers may experience pressures to meet delivery deadlines, potentially leading to skipped rest periods and disrupted sleep. This contributes to sleep deprivation, similar to the symptoms seen in research studies, including the one mentioned where 19 professional drivers were tested on performance after normal sleep and after being sleep deprived.