Bloomberg Business recently profiled the hazards of driving semi trucks, one of the most dangerous occupations in the United States.

For their article, Bloomberg interviewed a semi truck driver named Tracy L., who described her working conditions. Tracy’s days consisted of restless nights and back-to-back 14 hour days. Tracy says counted the hours until she was able to reach a Starbucks to caffeinate. The article chronicled the truck driver’s job over the course of a week as she crossed six states. Tracy recounted other semi truck drivers’ strategies for fending off sleep, including everything from mental games to amphetamines to cope with sleep deprivation.

The article continued that truckers work under conditions that are not conducive to a good night’s sleep. Drivers were reported to experience nearly-constant exhaustion as they worked 70 hours a week—the federally-mandated limit. Despite the fact that fatigue is a major contributor to semi truck crashes, lawmakers are pushing for new regulations to allow workers to spend as much as 82 hours per week driving semi trucks. Fatigue greatly reduces semi truck drivers’ ability to focus and respond to stimulus, making them more likely to suffer semi truck crashes.

Data from the U.S. Bureau of Labor holds that more than 500 semi truck drivers died on the road in 2013. But even more shocking, fatigued semi truck drivers were a contributing factor in more than 4,000 fatal accidents per year.

Fatigue is a serious concern for semi truck drivers. According to the Mayo Clinic, exhaustion can produce symptoms like inattention, poor concentration, loss of consciousness, decreased reaction time, and other symptoms. When someone is controlling a vehicle that weighs scores of tons at highway speed, these changes can be deadly. Many of these fatigue symptoms can alter the way a driver responds to their environment, making them less able to respond to driving conditions and other drivers. Additionally, drivers may fall asleep involuntarily, dosing off while driving. Falling asleep while driving a massive semi truck can easily cause a massive, deadly semi truck accident.

Semi truck accident lawsuits have been filed against semi truck drivers and the companies that manage them. Semi truck lawsuits allege that drivers are negligent in their behavior, putting deadlines and fatigue over safety. Along similar lines, some semi truck lawsuits allege that the firms that manage semi truck drivers contribute to serious semi truck accidents by setting unreasonable deadlines, forcing drivers to push themselves beyond their limits.