Middle schoolers do better when school starts — and ends — later, according to a North Carolina study by economist Finley Edwards described in Education Next.
. . . delaying school start times by one hour, from roughly 7:30 to 8:30, increases standardized test scores by at least 2 percentile points in math and 1 percentile point in reading.
Starting early has the most effect on older middle schoolers, supporting the theory that hormonal changes make it hard for adolescents to get to sleep in the early evening, Edwards writes. Students get more sleep and have fewer absences. But late starts have other advantages: With less unsupervised time after school, latebirds spend more time on homework and watch less TV.
“The effect of a later start time in both math and reading is more than twice as large for students in the bottom third of the test-score distribution than for students in the top third,” Edwards found.
Start times had no effect on elementary students, the study found, but elementary schools start later than middle schools, so that could obscure the effect.
Districts could swap elementary and secondary school start times to improve achievement without spending more on busing, Edwards suggests. Or districts could invest in more buses to start all schools at 8:30 or later. The achievement gain would be similar to the effect of cutting class sizes at a fraction of the cost.