Should middle and high schools start after 8:30 a.m.?

Adolescents often sleep later because puberty shifts melatonin release, and an international review found that greater social jetlag is linked to higher anxiety in teenagers. Researchers from the University of Southampton reviewed 18 studies and meta-analyzed data from 12 studies covering 235,526 adolescents. Major U.S. medical organizations say middle and high schools should start at or after 8:30 a.m., and the article says experts view enough sleep as essential for learning, memory and emotional regulation.

The review was published in Sleep Medicine Reviews and examined adolescents aged 12 to 18.

The meta-analysis included data from 12 studies involving 235,526 adolescents.

The American Academy of Pediatrics and the American Academy of Sleep Medicine both recommend that middle and high school classes begin at or after 8:30 a.m.

The American Academy of Sleep Medicine recommends that teenagers aged 13 to 18 get eight to 10 hours of sleep per day.

The article says deep sleep helps consolidate and retain information learned during the day, while insufficient sleep can hurt concentration, learning, memory, emotional regulation, impulse control and judgment.

Published Sep 4, 2026 12:05 am KST

As adolescents go through puberty, the timing of melatonin release — the hormone that promotes sleep — tends to shift later. As a result, teenagers often find themselves falling asleep and waking up later.

However, when schools start early in the morning, adolescents are often required to wake up earlier than their natural body clocks would prefer. This is one reason why many teenagers sleep late on weekends.

A recent study published in the international journal Sleep Medicine Reviews found that this difference in sleep schedules between weekdays and weekends, known as “social jetlag,” is associated with anxiety among adolescents.

Researchers from the University of Southampton’s department of psychology systematically reviewed studies examining the relationship between social jetlag and anxiety in adolescents aged 12 to 18. A total of 18 studies were included in the review, while data from 12 of those studies involving 235,526 adolescents was included in a meta-analysis.

The researchers found that adolescents with greater differences between their weekday and weekend sleep schedules tended to report higher levels of anxiety. Although the association between the two factors was small, it was statistically significant.

The researchers cautioned, however, that the study identified an association rather than proving that social jetlag directly causes anxiety.

“Nevertheless, these findings highlight the importance of maintaining consistent sleep and wake times throughout the week, including on weekends,” the researchers said. They also noted that school start times should be reconsidered in light of the biological changes in sleep patterns that occur during adolescence.

In the United States, major medical organizations have long recommended that middle and high schools start no earlier than 8:30 a.m. The American Academy of Pediatrics and the American Academy of Sleep Medicine (AASM) both recommend that classes for middle and high school students begin at or after 8:30 a.m. The AASM recommends that teenagers aged 13 to 18 get eight to 10 hours of sleep per day.

During puberty, adolescents undergo biological changes that shift their circadian rhythms later, making them naturally inclined to feel sleepy later at night and wake up later in the morning. Experts therefore say that simply telling teenagers to go to bed earlier may not be enough to ensure they get sufficient sleep.

Adequate sleep is also essential for the developing adolescent brain. During adolescence, brain functions involved in learning and memory, emotional regulation and decision-making continue to develop.

Deep sleep, in particular, plays an important role in consolidating and retaining information acquired during the day. In contrast, insufficient sleep can negatively affect not only concentration, learning and memory, but also emotional regulation, impulse control and judgment.

This article from Kormedi.com, Korea’s top health care and medical portal, is translated by a generative AI system and edited by The Korea Times.

青少年通常会睡得更晚，因为青春期会改变褪黑激素的分泌规律。一项国际综述发现，社交时差越大，青少年的焦虑程度也越高。南安普顿大学的研究人员回顾了18项研究，并对其中12项研究的数据进行了荟萃分析，这些研究涵盖了235,526名青少年。美国主要医疗机构建议中学和高中应该在早上8:30或之后开始上课。文章指出，专家认为充足的睡眠对于学习、记忆和情绪调节至关重要。

该综述发表在《睡眠医学评论》上，研究对象为 12 至 18 岁的青少年。

该荟萃分析纳入了 12 项研究的数据，涉及 235,526 名青少年。

美国儿科学会和美国睡眠医学会均建议初中和高中的课程应在上午 8:30 或之后开始。

美国睡眠医学会建议 13 至 18 岁的青少年每天睡眠时间为 8 至 10 小时。

文章指出，深度睡眠有助于巩固和保留白天学习到的信息，而睡眠不足会损害注意力、学习能力、记忆力、情绪调节能力、冲动控制能力和判断力。

发布于2026年9月4日凌晨12:05（韩国标准时间）

随着青少年进入青春期，褪黑激素（一种促进睡眠的激素）的分泌时间往往会推迟。因此，青少年常常会发现自己入睡和醒来的时间都比平时晚。

然而，由于学校早上很早就开始上课，青少年往往被迫比他们自然的生物钟更早起床。这也是许多青少年周末睡懒觉的原因之一。

最近发表在国际期刊《睡眠医学评论》上的一项研究发现，工作日和周末睡眠时间的差异（被称为“社交时差”）与青少年的焦虑有关。

南安普顿大学心理学系的研究人员系统地回顾了有关 12 至 18 岁青少年社交时差与焦虑之间关系的研究。该综述共纳入 18 项研究，其中 12 项研究的数据（涉及 235,526 名青少年）被纳入荟萃分析。

研究人员发现，工作日和周末睡眠时间差异较大的青少年往往焦虑程度更高。虽然这两个因素之间的关联性较弱，但具有统计学意义。

不过，研究人员也提醒说，这项研究只是发现了一种关联，而不是证明社交时差直接导致焦虑。

研究人员表示：“尽管如此，这些发现凸显了保持规律作息时间的重要性，包括周末在内。”他们还指出，鉴于青少年时期睡眠模式的生物学变化，学校的作息时间应该重新考虑。

在美国，各大医疗机构长期以来一直建议中学和高中的上课时间不早于上午 8:30。美国儿科学会和美国睡眠医学会 (AASM) 都建议中学和高中学生的课程在上午 8:30 或之后开始。AASM 建议 13 至 18 岁的青少年每天睡眠 8 至 10 小时。

青春期期间，青少年会经历一系列生理变化，导致他们的昼夜节律推迟，使他们自然而然地倾向于晚睡晚起。因此，专家指出，仅仅告诉青少年早点睡觉可能不足以确保他们获得充足的睡眠。

充足的睡眠对青少年大脑发育至关重要。在青春期，大脑中与学习记忆、情绪调节和决策相关的功能仍在不断发育。

深度睡眠尤其在巩固和记忆白天获取的信息方面发挥着重要作用。相反，睡眠不足不仅会对注意力、学习和记忆产生负面影响，还会影响情绪调节、冲动控制和判断力。

本文来自韩国顶级医疗保健门户网站 Kormedi.com，由人工智能生成系统翻译，并由《韩国时报》编辑。