The real reasons later school start times are effective

Two researchers explain how tardiness and discipline problems are linked to start times in high schools

In the U.S., 90 percent of high school students start their school day between 7:30 a.m. and 8:45 a.m. But is that the wisest approach? More recently, later start times have been advocated because adolescents have sleep-wake cycles that are delayed by puberty. For these students, in fact, peak performance has been shown to occur later in the day. Other studies show that two-thirds of adolescents on average get up to two hours less sleep than they need for optimal functioning. Maybe there’s a good reason many teens aren’t morning people.

We recently conducted a new study that used a longitudinal approach to measure the effect of delayed high school start times on students’ sleep, achievement and health — and whether changes persist. Our results suggest that delaying high school start times can robustly and persistently improve two variables that affect students, teachers, and administrators alike — tardiness and disciplinary problems in the classroom.

These results are consistent with many past studies that examined start time changes, adding further support to recommendations by the American Academy of Pediatricians that high schools should not start the school day until 8:30 a.m. or later.…Read More