Young drivers (under age 25) are much more likely than other adults to be involved in drowsy-driving crashes. Part of the reason for this is thought to result from a biologically driven “sleep phase shift,” wherein adolescents naturally begin to fall asleep later, consequently needing to sleep longer in the mornings in order to obtain sufficient rest. One promising approach to reducing drowsy driving crashes is designed to address this problem among high school age drivers is to move school start times to a later hour, e.g., 8:45 or 9 a.m. rather than 7:30–8:00 a.m. Preliminary findings from counties that have done this show reductions in teen driver crashes.
There are several possible explanations for why altered school start times might affect teen crash rates. And there are a number of other pertinent questions, the most prominent of which is whether such effects, if real, endure or erode as teens adapt to the shifted school start times. A study is currently under way to answer these questions about a potentially important policy approach to reducing teen driver crashes.