The Effects of School Start Time on Educational Outcomes: Evidence from the 9 O'clock Attendance Policy in South Korea

This study estimates the effects of school start time on sleep time, time use, and educational achievement of high school students. Gyeonggi province, the largest province in South Korea, has implemented the 9 O'clock Attendance Policy, which has delayed school start times to 9:00 AM since September 2014. Changes in the above outcomes before and after the policy implementation are compared between Gyeonggi and other provinces which do not implement the policy. The difference-in-differences estimation results show that the policy increases sleep time, and this is mainly from delayed wake-up time. The policy also reduces adolescents' time use for computer games. The estimation results using administrative national exam data show that the 9 O'clock Attendance Policy does not significantly affect academic achievement.