Each spring, most people, including California residents, set their clocks ahead one hour. Research based on the U.S. Department of Labor and Mine Safety and Health Administration injury data from 1983 to 2006 suggests that the hour of sleep lost due to daylight saving time could be tied to the 5.7 percent spike in workplace injuries that occurred the day following each daylight saving time change. In addition to a greater number of injuries, researchers say injuries were more severe and caused a loss of nearly 68 percent more workdays.