Yawn! Teenagers have always been sleep-deprived, right? Researchers say that adolescent bodies work differently than kids or adults, making teens more likely to stay up late at night and wake up later. In response, a handful of schools around Los Angeles are starting classes later in the day, hoping that students will get more sleep. Studies support this idea. Sleep psychologist John Cline tells us why later school start times make students more alert and less irritable. Not only does academic performance improve, teens who can sleep in even get into fewer car accidents.