ABSTRACT

This paper examines how delaying school start time to 9 o’clock affected the time use and health of secondary-school students in South Korea. To identify the causal effects of delaying school start time, we used a difference-in-differences methodology with two nationally representative datasets to take advantage of a unique natural experiment in South Korea. We found that the policy led students to sleep 16.1 min more on weekdays and 7.6 min less a day over the weekend, increasing sleep satisfaction among the affected students. Furthermore, the policy contributed to increased growth and improved mental health. However, the effects of the policy were not uniform across subgroups. In terms of time use, students from the highest socioeconomic group increased their sleep duration most. In contrast, students from the middle and lowest socioeconomic categories increased their use of electronic devices and decreased their study time compared to students from the highest socioeconomic group. We provide evidence that these behavioural differences by socioeconomic group could be related to the degree of parental monitoring and available economic resources.

摘要

本文研究了延迟上学时间到9点钟如何影响韩国中学生的时间使用和健康状况。为了确定延误开学时间的因果关系，我们使用了两个国家代表性数据集的差异差异方法，以利用韩国独特的自然实验优势。我们发现，该政策使学生在工作日的睡眠时间增加了16.1分钟，在周末的睡眠时间减少了7.6分钟，从而提高了受影响学生的睡眠满意度。此外，该政策有助于增长和改善心理健康。但是，该政策的效果在各个子组之间并不统一。在时间上，社会经济地位最高的学生的睡眠时间最多。相反，与社会经济地位最高的学生相比，社会经济地位中等和最低的学生增加了对电子设备的使用，缩短了学习时间。我们提供的证据表明，社会经济群体的这些行为差异可能与父母监护的程度和可用的经济资源有关。