California residents should be aware of the risk they run when they drive after getting less than seven hours of sleep. Experts recommend between seven and nine hours of sleep a night. However, one in three adult drivers is not meeting this goal, according to research by the U.S. Department of Transportation and various agencies.

An estimated 7 percent of all motor vehicle crashes in the U.S. are caused by drowsy driving. That means that the behavior is responsible for about 330,000 accidents every year. Moreover, drowsy driving accounts for 16 percent of all fatal crashes.

As for the actual risk that drowsy drivers run, a study that was published in the journal SLEEP has been able to quantify it. Specifically, people who get six, five or four hours of sleep raise their risk for a car crash 1.3, 1.9 and 2.9 times respectively. With less than four hours of sleep, drivers raise it a dramatic 15.1 times and become the most susceptible to single-vehicle crashes. Single-vehicle crashes result in more injuries and deaths than other types of crashes, according to the U.S. DoT.

Researchers emphasize how sleep deprivation leads to inattention, failure to judge traffic gaps and other issues. Drivers who travel three hours without a break also endanger themselves. Previous studies show how sleep apnea raises crash risk even when drivers don’t feel drowsy.

When drivers ignore these risks and become drowsy behind the wheel, they will be to blame for any accidents they cause. Victims can see a lawyer who works in auto accident law to determine if they have a strong case. Once they retain an attorney, he or she could bring in investigators and other experts to build the case up. The lawyer could then begin negotiations with the defendant’s car insurance company for a fair settlement.