What the Brain Does While We Sleep

人的一辈子中，大约有三分之一的时间是在睡觉中度过的。

Rén (second tone, rising) de (neutral tone) yíbèizi (second tone, rising) zhōng, (first tone, high and level) dàyuē (fourth tone, falling) yǒu (third tone, dipping) sān (first tone, high and level) fēn (first tone, high and level) zhī (first tone, high and level) yī (first tone, high and level) de (neutral tone) shíjiān (second tone, rising) shì (fourth tone, falling) zài (fourth tone, falling) shuìjiào (fourth tone, falling) zhōng (first tone, high and level) dùguò (fourth tone, falling) de. (neutral tone)

Over a lifetime, roughly a third of our time is spent asleep.

很长时间以来，人们一直以为，睡觉只是为了让身体休息，大脑在这段时间里也停止了工作。

Hěn (third tone, dipping) cháng (second tone, rising) shíjiān (second tone, rising) yǐlái, (third tone, dipping) rénmen (second tone, rising) yìzhí (fourth tone, falling) yǐwéi, (third tone, dipping) shuìjiào (fourth tone, falling) zhǐshì (third tone, dipping) wèile (fourth tone, falling) ràng (fourth tone, falling) shēntǐ (first tone, high and level) xiūxi, (first tone, high and level) dànǎo (fourth tone, falling) zài (fourth tone, falling) zhè (fourth tone, falling) duàn (fourth tone, falling) shíjiān (second tone, rising) li (neutral tone) yě (third tone, dipping) tíngzhǐ (second tone, rising) le (neutral tone) gōngzuò. (first tone, high and level)

For a long time people assumed that sleep was simply a way of resting the body, and that the brain stopped working for those hours too.

然而，科学家们通过研究发现，事实并不是这样。

Rán (second tone, rising) ér, (second tone, rising) kēxuéjiāmen (first tone, high and level) tōngguò (first tone, high and level) yánjiū (second tone, rising) fāxiàn, (first tone, high and level) shìshí (fourth tone, falling) bìng (fourth tone, falling) bú (second tone, rising) shì (fourth tone, falling) zhèyàng. (fourth tone, falling)

Research, however, has shown that this is not the case.

人睡着以后，大脑仍然非常活跃，它正在忙着做两件重要的事情。

Rén (second tone, rising) shuìzháo (fourth tone, falling) yǐhòu, (third tone, dipping) dànǎo (fourth tone, falling) réngrán (second tone, rising) fēicháng (first tone, high and level) huóyuè, (second tone, rising) tā (first tone, high and level) zhèngzài (fourth tone, falling) máng (second tone, rising) zhe (neutral tone) zuò (fourth tone, falling) liǎng (third tone, dipping) jiàn (fourth tone, falling) zhòngyào (fourth tone, falling) de (neutral tone) shìqing. (fourth tone, falling)

Once we fall asleep the brain is still very active, busy with two important jobs.

第一件事是整理记忆。

Dì (fourth tone, falling) yī (first tone, high and level) jiàn (fourth tone, falling) shì (fourth tone, falling) shì (fourth tone, falling) zhěnglǐ (third tone, dipping) jìyì. (fourth tone, falling)

The first is sorting memories.

白天我们看到、听到和学到的东西，一开始只是暂时保存在大脑里，很容易被忘记。

Báitiān (second tone, rising) wǒmen (third tone, dipping) kàn (fourth tone, falling) dào, (fourth tone, falling) tīng (first tone, high and level) dào (fourth tone, falling) hé (second tone, rising) xué (second tone, rising) dào (fourth tone, falling) de (neutral tone) dōngxi, (first tone, high and level) yì (fourth tone, falling) kāishǐ (first tone, high and level) zhǐshì (third tone, dipping) zànshí (fourth tone, falling) bǎocún (third tone, dipping) zài (fourth tone, falling) dànǎo (fourth tone, falling) li, (neutral tone) hěn (third tone, dipping) róngyì (second tone, rising) bèi (fourth tone, falling) wàngjì. (fourth tone, falling)

What we see, hear and learn during the day is at first stored in the brain only temporarily, and is easily forgotten.

在睡觉的过程中，大脑会把其中有用的内容选出来，把它们保存得更久。

Zài (fourth tone, falling) shuìjiào (fourth tone, falling) de (neutral tone) guòchéng (fourth tone, falling) zhōng, (first tone, high and level) dànǎo (fourth tone, falling) huì (fourth tone, falling) bǎ (third tone, dipping) qízhōng (second tone, rising) yǒu (third tone, dipping) yòng (fourth tone, falling) de (neutral tone) nèiróng (fourth tone, falling) xuǎn (third tone, dipping) chūlái, (first tone, high and level) bǎ (third tone, dipping) tāmen (first tone, high and level) bǎocún (third tone, dipping) de (neutral tone) gèng (fourth tone, falling) jiǔ. (third tone, dipping)

During sleep the brain picks out what is useful and keeps it for longer.

有一个实验证明了这一点：研究人员让两批学生学习同样的词语，第一批学完以后马上去睡觉，第二批一直不睡觉。结果第二天，第一批学生记住的词语明显比第二批多。

Yǒu (third tone, dipping) yí (second tone, rising) ge (neutral tone) shíyàn (second tone, rising) zhèngmíng (fourth tone, falling) le (neutral tone) zhè (fourth tone, falling) yìdiǎn: (fourth tone, falling) yánjiū (second tone, rising) rényuán (second tone, rising) ràng (fourth tone, falling) liǎng (third tone, dipping) pī (first tone, high and level) xuésheng (second tone, rising) xuéxí (second tone, rising) tóngyàng (second tone, rising) de (neutral tone) cíyǔ, (second tone, rising) dì (fourth tone, falling) yī (first tone, high and level) pī (first tone, high and level) xué (second tone, rising) wán (second tone, rising) yǐhòu (third tone, dipping) mǎshàng (third tone, dipping) qù (fourth tone, falling) shuìjiào, (fourth tone, falling) dì (fourth tone, falling) èr (fourth tone, falling) pī (first tone, high and level) yìzhí (fourth tone, falling) bú (second tone, rising) shuìjiào. (fourth tone, falling) Jiéguǒ (second tone, rising) dì (fourth tone, falling) èr (fourth tone, falling) tiān, (first tone, high and level) dì (fourth tone, falling) yī (first tone, high and level) pī (first tone, high and level) xuésheng (second tone, rising) jìzhù (fourth tone, falling) de (neutral tone) cíyǔ (second tone, rising) míngxiǎn (second tone, rising) bǐ (third tone, dipping) dì (fourth tone, falling) èr (fourth tone, falling) pī (first tone, high and level) duō. (first tone, high and level)

One experiment showed this. Researchers had two groups of students learn the same words; the first group went to sleep straight after learning, the second stayed awake. The next day the first group remembered clearly more words than the second.

这说明，学习以后好好睡一觉，比一直学下去效果更好。

Zhè (fourth tone, falling) shuōmíng, (first tone, high and level) xuéxí (second tone, rising) yǐhòu (third tone, dipping) hǎohǎo (third tone, dipping) shuì (fourth tone, falling) yí (second tone, rising) jiào, (fourth tone, falling) bǐ (third tone, dipping) yìzhí (fourth tone, falling) xué (second tone, rising) xiàqù (fourth tone, falling) xiàoguǒ (fourth tone, falling) gèng (fourth tone, falling) hǎo. (third tone, dipping)

In other words, a good sleep after studying does more than carrying on studying.

第二件事是“打扫”大脑。

Dì (fourth tone, falling) èr (fourth tone, falling) jiàn (fourth tone, falling) shì (fourth tone, falling) shì (fourth tone, falling) “dǎsǎo” (third tone, dipping) dànǎo. (fourth tone, falling)

The second job is “cleaning” the brain.

大脑工作一天以后，会产生一些对身体不好的物质。

Dànǎo (fourth tone, falling) gōngzuò (first tone, high and level) yì (fourth tone, falling) tiān (first tone, high and level) yǐhòu, (third tone, dipping) huì (fourth tone, falling) chǎnshēng (third tone, dipping) yìxiē (fourth tone, falling) duì (fourth tone, falling) shēntǐ (first tone, high and level) bù (fourth tone, falling) hǎo (third tone, dipping) de (neutral tone) wùzhì. (fourth tone, falling)

After a day’s work the brain produces substances that are bad for the body.

研究人员发现，人在睡觉的时候，大脑处理这些物质的速度比白天快得多。

Yánjiū (second tone, rising) rényuán (second tone, rising) fāxiàn, (first tone, high and level) rén (second tone, rising) zài (fourth tone, falling) shuìjiào (fourth tone, falling) de (neutral tone) shíhou, (second tone, rising) dànǎo (fourth tone, falling) chǔlǐ (third tone, dipping) zhèxiē (fourth tone, falling) wùzhì (fourth tone, falling) de (neutral tone) sùdù (fourth tone, falling) bǐ (third tone, dipping) báitiān (second tone, rising) kuài (fourth tone, falling) de (neutral tone) duō. (first tone, high and level)

Researchers have found that while we sleep, the brain deals with these substances much faster than during the day.

如果长时间睡得不够，这些物质就会越来越多，人的记忆和判断能力都会变差。

Rúguǒ (second tone, rising) cháng (second tone, rising) shíjiān (second tone, rising) shuì (fourth tone, falling) de (neutral tone) bú (second tone, rising) gòu, (fourth tone, falling) zhèxiē (fourth tone, falling) wùzhì (fourth tone, falling) jiù (fourth tone, falling) huì (fourth tone, falling) yuè (fourth tone, falling) lái (second tone, rising) yuè (fourth tone, falling) duō, (first tone, high and level) rén (second tone, rising) de (neutral tone) jìyì (fourth tone, falling) hé (second tone, rising) pànduàn (fourth tone, falling) nénglì (second tone, rising) dōu (first tone, high and level) huì (fourth tone, falling) biàn (fourth tone, falling) chà. (fourth tone, falling)

If we go without enough sleep for a long time, these substances build up, and both memory and judgement get worse.

所以，考试的前一天晚上不睡觉复习，其实并不是一个聪明的办法。

Suǒyǐ, (third tone, dipping) kǎoshì (third tone, dipping) de (neutral tone) qián (second tone, rising) yì (fourth tone, falling) tiān (first tone, high and level) wǎnshang (third tone, dipping) bú (second tone, rising) shuìjiào (fourth tone, falling) fùxí, (fourth tone, falling) qíshí (second tone, rising) bìng (fourth tone, falling) bú (second tone, rising) shì (fourth tone, falling) yí (second tone, rising) ge (neutral tone) cōngming (first tone, high and level) de (neutral tone) bànfǎ. (fourth tone, falling)

So staying up all night to revise before an exam is not, in fact, a clever idea.

那么，一个人每天睡多长时间最合适呢？

Nàme, (fourth tone, falling) yí (second tone, rising) ge (neutral tone) rén (second tone, rising) měi (third tone, dipping) tiān (first tone, high and level) shuì (fourth tone, falling) duō (first tone, high and level) cháng (second tone, rising) shíjiān (second tone, rising) zuì (fourth tone, falling) héshì (second tone, rising) ne? (neutral tone)

So how long should a person sleep each day?

专家建议，大人一般每天应该睡七到八个小时，正在长身体的青少年还需要更多。

Zhuānjiā (first tone, high and level) jiànyì, (fourth tone, falling) dàrén (fourth tone, falling) yìbān (fourth tone, falling) měi (third tone, dipping) tiān (first tone, high and level) yīnggāi (first tone, high and level) shuì (fourth tone, falling) qī (first tone, high and level) dào (fourth tone, falling) bā (first tone, high and level) ge (neutral tone) xiǎoshí, (third tone, dipping) zhèngzài (fourth tone, falling) zhǎng (third tone, dipping) shēntǐ (first tone, high and level) de (neutral tone) qīngshàonián (first tone, high and level) hái (second tone, rising) xūyào (first tone, high and level) gèng (fourth tone, falling) duō. (first tone, high and level)

Experts advise that adults should generally sleep seven to eight hours a day, and that teenagers, who are still growing, need more.

不过，睡得好不好，不只看时间长短，还要看质量。

Búguò, (second tone, rising) shuì (fourth tone, falling) de (neutral tone) hǎo (third tone, dipping) bu (neutral tone) hǎo, (third tone, dipping) bù (fourth tone, falling) zhǐ (third tone, dipping) kàn (fourth tone, falling) shíjiān (second tone, rising) chángduǎn, (second tone, rising) hái (second tone, rising) yào (fourth tone, falling) kàn (fourth tone, falling) zhìliàng. (fourth tone, falling)

But whether you sleep well depends not only on how long, but also on the quality.

有的人虽然睡了九个小时，但是夜里常常醒，第二天仍然觉得很累。

Yǒude (third tone, dipping) rén (second tone, rising) suīrán (first tone, high and level) shuì (fourth tone, falling) le (neutral tone) jiǔ (third tone, dipping) ge (neutral tone) xiǎoshí, (third tone, dipping) dànshì (fourth tone, falling) yèli (fourth tone, falling) chángcháng (second tone, rising) xǐng, (third tone, dipping) dì (fourth tone, falling) èr (fourth tone, falling) tiān (first tone, high and level) réngrán (second tone, rising) juéde (second tone, rising) hěn (third tone, dipping) lèi. (fourth tone, falling)

Some people sleep nine hours yet wake up often in the night, and still feel exhausted the next day.

睡觉以前少看手机，每天按时睡觉和起床，都能帮助我们睡得更好。

Shuìjiào (fourth tone, falling) yǐqián (third tone, dipping) shǎo (third tone, dipping) kàn (fourth tone, falling) shǒujī, (third tone, dipping) měi (third tone, dipping) tiān (first tone, high and level) ànshí (fourth tone, falling) shuìjiào (fourth tone, falling) hé (second tone, rising) qǐchuáng, (third tone, dipping) dōu (first tone, high and level) néng (second tone, rising) bāngzhù (first tone, high and level) wǒmen (third tone, dipping) shuì (fourth tone, falling) de (neutral tone) gèng (fourth tone, falling) hǎo. (third tone, dipping)

Looking at your phone less before bed and going to bed and getting up at regular times both help us sleep better.

从这个意义上说，睡觉并不是浪费时间，而是在为第二天的学习和工作做准备。

Cóng (second tone, rising) zhè (fourth tone, falling) ge (neutral tone) yìyì (fourth tone, falling) shang (neutral tone) shuō, (first tone, high and level) shuìjiào (fourth tone, falling) bìng (fourth tone, falling) bú (second tone, rising) shì (fourth tone, falling) làngfèi (fourth tone, falling) shíjiān, (second tone, rising) ér (second tone, rising) shì (fourth tone, falling) zài (fourth tone, falling) wèi (fourth tone, falling) dì (fourth tone, falling) èr (fourth tone, falling) tiān (first tone, high and level) de (neutral tone) xuéxí (second tone, rising) hé (second tone, rising) gōngzuò (first tone, high and level) zuò (fourth tone, falling) zhǔnbèi. (third tone, dipping)

Seen this way, sleep is not a waste of time; it is preparation for the next day’s study and work.