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Circadian Rhythms: Our Built-in Alarm Clocks 生理时钟知多少

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An alarm goes off with a loud beeping sound. You blindly search for the source and slam the button to ___1___ the noise. These noisy clocks are a necessity in our lives, but what most people don’t realize is that we already come with an internal alarm clock ___2___ inside our brains. This is what is known as “circadian rhythms.” These rhythms are important in determining the sleeping and feeding patterns ___3___ all animals over a 24-hour period.

闹钟哔声大作，你摸索着寻找声音来源，然后猛然按下闹钟按钮，结束声响。这些扰人清梦的时钟是我们生活必需品，但大部分人不晓得的是，人脑已有内建的闹钟，也就是所谓的「生物日夜节律（生理时钟）」。这些节律对所有动物24小时内的睡眠和进食模式具有决定性的影响。

“Circadian” comes from the Latin word for “around the clock.” Circadian rhythms are controlled by the amount of light we ___4___ by photoreceptors at the back of our eyes. Specialized nerves are signaled by the light and tell our brains ___5___ of the sleep-inducing hormone, melatonin, to produce. This is why people sleep better at night, when the light is the ___6___. But why then do some people seem to be “early birds” and others “night ___7___”?

Circadian由拉丁文中表「全天候」之意的字衍生而来。生物日夜节律由视网膜底层的感光器所接收的光线量来控制。专司其职的神经接收光线的信号后，便告诉大脑该分泌出多少睡眠荷尔蒙－「褪黑激素」。这就是人们在夜晚光线最微弱时睡眠较佳的原因。但为什么有些人是「早起的鸟儿」，而有些却是「夜猫子」呢？

Researchers extracted DNA samples from 500 ___8___ to determine if they were morning or evening people. They isolated a gene called Period 3, which comes in two ___9___. A person with the shorter gene prefers nighttime while a person with the longer gene prefers daylight. With more people working around the clock, it pays to know that some may be better suited to the night shift if they have a ___10__ predisposition towards evening hours. It would also seem the old proverb of “an early bird get the worm” doesn’t always apply to everyone.

研究人员采样500名受试者的DNA样本，藉以判别他们是早起或晚睡型的人。研究员分离出一种具两种形式、名为Period 3的基因。该基因较短的人偏爱在夜间活动，而该基因较长的人则较喜爱在白天活动。由于越来越多人从事全天性的工作，因此得知哪些人在先天基因倾向上较适合夜班，是非常值得的。而「早起的鸟儿有虫吃」这句谚语也不尽然适用于每个人了。

−by Ryan Campbell

Vocabulary

单词发音

built-in 固定的; 内在的; 嵌入的

go off 发出巨响  to make a noise; sound

slam [slæm] v. 猛地关上

internal [ɪnˋtɝn!] adj. 内的，内部的

hormone [ˋhɔrmon] n. 荷尔蒙

extract [ɪkˋstrækt] v. 提炼; 榨取

isolate [ˋaɪs!͵et] v. 使脱离

apply to 适用于

More Information

单词发音

circadian [sɚˋkedɪən] adj. 全天的; 〔尤指体内变化〕昼夜节律的﹐生理节奏的﹐以24小时为周期的

photoreceptor 光感受器，感光器

specialized [ˋspɛʃəl͵aɪzd] adj. 专门的；专科的

melatonin [ˌmɛləˈtonɪn] n. 褪黑激素

why then 那是为什么

around the clock 整天整夜, 夜以继日 lasting or continuing throughout the entire 24 hours of the day; continuous

pay [pe] v. 有利，划算  to be profitable or worthwhile

night shift 夜班；夜班工人

predisposition [͵pridɪspəˋzɪʃən] n. 倾向；素质

Answer