Rise and Shine The Effect of School Start Times on Academic Performance from Childhood through Puberty

Abstract

American teenagers are chronically sleep deprived. As children enter puberty, physiological changes delay the onset of sleep and make it more difficult to wake up early in the morning. By the end of middle school, there is a large disconnect between biological sleep patterns and early-morning school schedules: one study found that students lose as much as two hours of sleep per night during the school year compared to the summer months, when they can better control their sleep schedules. Such deficits may have big implications for learning and cognition. Important memory formation and consolidation processes occur overnight, as the brain replays patterns of activity exhibited during learning. Could something as simple as changing when school starts each day really make a difference in how much students learn? And which students would benefit most from a later start time? The authors consider differences between sunrise and school start times among a group of public schools in northern Florida's "Panhandle," which straddles the central and eastern time zones. In this region, sunrise times differ, but school start times do not fully adjust for this difference. Students may start school at the same hour on the clock but not at the same "time"--those in the later time zone could have as much as one additional hour of early-morning daylight before school compared to their neighbors in the earlier zone. How does this affect their performance in school? The authors compare test scores for students between the ages of 8 and 15 who move from one time zone to the other and find substantial differences, especially for adolescents. A one-hour delay in start times relative to sunrise increases math scores by 8 percent of a standard deviation for adolescents--the equivalent of roughly three months of student learning--but by only 1 percent of a standard deviation for younger children. The effects on reading scores are similar, but smaller. These findings are the first to quantify the potential academic benefits of changing high-school start times--a seemingly straightforward policy that districts can find difficult to implement.