School start times may be more than just annoying for teenagers: They could actually be dangerous, a study reported in the New York Times suggests. Researchers studying two demographically similar counties in Virginia found that crash rates among 16- to 18-year-olds were higher in the county where teens must wake up earlier. In Henrico County, where high school starts at 8:45 am, the crash rate was 37.9 per thousand in the 2009-2010 school year; in Chesterfield County, where school starts at 7:20, the rate was 48.8 per thousand.
Adult crash rates, on the other hand, "did not differ between counties," the researchers write in the Journal of Clinical Sleep Medicine. The study doesn't, however, prove that the early start times caused the accidents, the lead author tells the Times; researchers didn't look other potential factors like sleep habits or distance traveled in each county. But a pediatric sleep specialist offered a warning in the same newspaper last month: "The level of impairment associated with sleep-deprived driving is equivalent to driving drunk," she noted. "Would you let a kid drive who just consumed three or four beers? Well, guess what? Kids do that every day." (Read more sleep stories.)