A's from Zzzz's? The Causal Effect of School Start Time on the Academic Achievement of Adolescents
利用美国空军学院的课程时间政策变化和新生随机分班，发现将上课时间推迟50分钟能显著提升学生成绩，效果约等于教师质量提高一个标准差。
Recent sleep research finds that many adolescents are sleep-deprived because of both early school start times and changing sleep patterns during the teen years. This study identifies the causal effect of school start time on academic achievement by using two policy changes in the daily schedule at the US Air Force Academy along with the randomized placement of freshman students to courses and instructors. Results show that starting the school day 50 minutes later has a significant positive effect on student achievement, which is roughly equivalent to raising teacher quality by one standard deviation.