A study suggests that schools with earlier start times show an increased risk of teenagers crashing their cars. It all boils down to the requisite hours of sleep needed to function, say researchers. On average, teenagers need over nine —an amount that many teens don’t even come close to getting. The study took 2008 data from similar U.S. cities—Virginia Beach and Chesapeake—which have similar demographics but different school start times. The results of the study showed that accident rates were 41 percent higher in Virginia Beach where schools started earlier. Since teens are biologically programmed to go to sleep earlier, the amount of sleep teens get depends on what time they wake up in the morning. “Younger, inexperienced drivers don’t fare well with additional handicaps such as impaired alertness caused by having to get up earlier than is natural for them,” says sleep expert Dr. Barbara Phillips.