“赖床”一刻值千金

研究表明，青少年的睡眠节律往往比成年人滞后两到三个小时。但不幸的是，学校上课的时间对于他们来讲太早了，让他们很难睡个好觉。保守估计，将上学时间推迟至上午8:30可以给美国带来1400亿美元的收益。

测试中可能遇到的词汇和知识：

circadian [sɜː'keɪdiən] 昼夜节律的

secretion[sɪ'kriːʃn] 分泌, 分泌物

exacerbate [ɪɡ'zæsəbeɪt] 加重

unequivocal [ˌʌnɪ'kwɪvəkl] 确实的, 明白的

falter['fɔːltə(r) ] 迟疑；动摇

Why teenagers need more sleep（654 words）

By Anjana Ahuja

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.

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.

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.

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.

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.

Last month, however, a bill designed to enact such a change faltered in California. The bill, which has the backing of the Start School Later movement, a lobby group of parents, health professionals and policymakers, is likely to resurface in January. Many schools in other states have already acted.

All the evidence points to teen sleeping patterns being a consequence of biology, not attitude, according to Kyla Wahlstrom, an educational policy specialist at the University of Minnesota, who has studied this issue since 1996.

Delayed start times, Dr Wahlstrom says, have immediate and noticeable impacts, such as a reduced rate of teenage car crashes. One county in Kentucky saw the number of teenage crashes fall by 16 per cent in the two years after school starts were delayed by an hour, a reduction attributed to the drivers being more alert. The crash rate rose by 8 per cent across the state as a whole.

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.

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.

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.

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?”

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

请根据你所读到的文章内容，完成以下自测题目：

1.Which of the following statements about US school is true?

A.Many school in the US has already delayed their start time.

B.Some US school delayed start time to reduce rate of car crashes.

C.Most schools in the US begin at 7:00 in the morning.

D.Many US schools are puzzled by suicide and obesity problems.

答案(1)

2.Rand Corporation's report argues that delaying the start of school can bring all of the following benefits EXCEPT ?

A.Improving academic performance.

B.Reducing rate of teenage car crashes.

C.Reducing risks of suicide and obesity .

D.Generating a $9.3bn benefit a year.

答案(2)

3.What is the Start School Later movement？

A.A movement in California advocating for British Summer Time.

B.A movement in California which seeks to shift school schedules.

C.A bill designed to delay school start times in California.

D.A lobby group of parents, health professionals and policymakers.

答案(3)

4.Scientists at the universities of Surrey and Harvard argues that ____.

A.delayed school starts can reduce teenager's exposure to artificial light.

B.turning down the lights in the evening helps teenagers get more sleep.

C.delayed school starts will lead to teenagers getting more sleep.

D.delayed school starts will not help teenagers to get more sleep.

答案(4)

* * *

(1)答案：A.Many school in the US has already delayed their start time.

解释：上个月，一项关于推迟上学时间的法案在加州未能在加州通过。但其他州的很多学校已经在这么做了。

(2)答案：C.Reducing risks of suicide and obesity .

解释：兰德公司的报告指出，推迟上学时间可以给美国带来每年93亿美元的收益，主要来自两方面：一方面提高学习成绩，另一方面减少交通事故发生率。

(3)答案：D.A lobby group of parents, health professionals and policymakers.

解释：“晚上学运动”是一个由父母、健康专家和政策制定者组成的游说团体。

(4)答案：B.turning down the lights in the evening helps teenagers get more sleep.

解释：萨里大学和哈佛大学的研究人员发现，在晚上关灯可以让青少年获得更多睡眠而无需改变上学时间。