一日之际真的在于晨？10点上学更有效

In the UK, the clocks go back by one hour on Sunday to mark the end of British Summer Time. Experts have been weighing up a more permanent time shift in our daily schedules, particularly for tired teenagers who struggle with early school starts.

每年入冬时，英国把时钟往后拨1个小时，这标志着夏令时结束。专家们在考虑对我们的日常作息时间作出更为永久性的调整，特别是针对那些艰难应对大清早上学的没睡醒的青少年。

The rethink on teen slumber is largely due to the emerging science on circadian rhythms. The genetics associated with body clocks earned this year’s Nobel Prize for physiology or medicine. The timing of release of the sleep hormone melatonin is thought to change with age: during adolescence, secretion begins late at night and continues until about 8am. The sleep rhythm of a teenager can lag an adult by two to three hours.

重新思考青少年的睡眠问题，在很大程度上是因为新兴的昼夜节律科学。与生物钟有关的基因研究赢得了今年的诺贝尔生理学或医学奖。人体释放睡眠荷尔蒙-褪黑激素的时间据信会随着年龄改变：在青春期，褪黑激素在深夜开始释放并持续到早上8点左右。青少年的睡眠节律可能比成年人晚两到三个小时。

A report by the Rand Corporation argues that, for adolescents, delaying the start of school to 8.30am or later could bring a $140bn benefit to the US economy over 15 years. Some US school days start as early as 7am.

兰德公司的一份报告认为，把青少年的上学时间推迟到8点30分或更晚，有望在未来15年给美国经济带来1400亿美元的效益。美国一些学校早上7点就开始上课了。

The gains, which amount to a dividend of $9.3bn a year, arise mainly from two predicted pay-offs: improved academic performance, which increases the likelihood of graduation and future work; and a reduction in car crashes, which means more students make it into the future labour supply.

这项收益-相当于每年93亿美元-主要来自两个预计回报：一是学习成绩提高，从而增加毕业和未来就业的可能性；二是车祸事故减少，这意味着会有更多学生安好地加入未来的劳动力队伍。

Marco Hafner, a Rand economist, says the gains could be even higher because the calculation of benefits were on the conservative side. The input to the macroeconomic simulation did not factor in other phenomena, such as the risks of suicide and obesity that are believed to be exacerbated by sleep deprivation.

兰德的经济学家马尔科.哈夫纳表示，因为计算效益时偏向保守，所以实际效益可能更高。宏观经济模拟的输入没有考虑其他现象，比如自杀和肥胖风险-据信睡眠不足会加剧这类风险。

Rand, which used data from 47 US states, concluded that teenage sleep deprivation should be regarded as an economic problem with a possible solution. The financial rewards, it says, would quickly outweigh any associated costs of fixing it, such as rescheduling bus routes or extending after-school clubs.

兰德利用美国47个州的数据得出结论认为，青少年睡眠不足应该被视为一个可能解决的经济问题。该公司表示，经济回报将很快超过解决该问题的相关成本，比如重新安排公交车时间表，或延长课外兴趣小组的时间。

A similar debate has been stirring in the UK. In 2015, Paul Kelley, a professor at the Sleep and Circadian Neuroscience Institute at Oxford university, suggested that 16-year-olds should start no earlier than 10am. For 18-year-olds, an 11am start is preferable. Early starts, he says, mean pupils are usually performing suboptimally.

类似辩论也在英国升温。2015年，牛津大学睡眠和昼夜节律神经科学研究所教授保罗.凯利建议，16岁学生的上学时间不应早于上午10点。对于18岁的学生，11点上学更好。他表示，过早上学通常意味着学生表现欠佳。

Not everyone concurs: scientists at the universities of Surrey and Harvard dispute that delayed starts will lead to teenagers getting more sleep. One unintended consequence, for example, might be students being exposed to artificial light for longer because of later bedtimes.

并非所有人都同意该结论：萨里大学和哈佛大学的科学家质疑推迟上学时间将导致青少年睡眠时间增加的结论。例如，一个意外后果可能是因为上床睡觉时间推迟，学生们暴露在人造灯光下的时间更长。

Based on mathematical modelling, this contrary study suggested that turning down the lights in the evening would allow teenagers to get more sleep without the need for a change to the school day. The time that students spend on their mobile phones and other devices also crops up regularly as a complicating factor in teenage sleep studies.

这项相反的研究基于数学建模，它似乎表明，晚上早些关灯就可以让青少年的睡眠时间增加，而无需改变上学时间。在青少年睡眠研究中，学生们花在手机及其他设备上的时间也经常会冒出来，成为一个使问题复杂化的因素。

Nevertheless, one London head of an independent school has chosen to push back the start of the day for sixth-formers to 9.30am. Explaining his decision in an article for the Times Educational Supplement, Jonathan Taylor pointed out that the 9-to-5 mode of working was disappearing anyhow. He criticised educators who clung to an early start out of “a misguided notion of traditional self-discipline?.?.?.?is it really more worthy to learn maths at 8.30am than 5pm?”

尽管如此，伦敦一家私立学校的校长选择把高中生的上学时间推迟到早上9点30分。乔纳森.泰勒在为《泰晤士报教育增刊》撰写的文章中解释了自己的决定，他指出，朝九晚五的工作模式反正将要终结。他指责那些坚持早上学的教育家是出于“自律这种具有误导性的传统理念……难道早上8点30分学数学，就一定比下午5点学数学更有价值吗？”

Attendance and punctuality, Mr Taylor enthused, had improved – and the teenagers made for jollier company. Heaven knows, we could all do with happier teens.

泰勒兴奋地表示，推迟上学时间后，学生的出勤率提高，迟到率下降，而且青少年们更容易相处了。天知道，我们都需要更快乐的青少年。