Sleep
It's clear that everyone needs to sleep. Most people rarely think about how and why they sleep, however. We know that if we sleep well, we feel rested. If we don't sleep enough, we often feel tired and irritable.
It seems there are two purposes of sleep: physical rest and emotional and psychological rest. We need to rest our bodies and minds. Both are important in order for us to be healthy. Each night we alternate between two kinds of sleep: active sleep and passive sleep. The passive sleep gives our body the rest that's needed and prepares us for active sleep, in which dreaming occurs.
Throughout the night, people alternate between passive and active sleep. The brain rests, then it becomes active, then dreaming occurs. The cycle is repeated: the brain rests, then it becomes active, then dreaming occurs. This cycle is repeated several times throughout the night. During eight hours of sleep, people dream for a total of one and half hours on the average.
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此文說明了人們為什麽要睡眠，以及睡眠狀態中做夢的情況。從第三段中可以看出，睡眠中做夢是正常情況，而非有些人所認為的：做夢會影響休息。文中所用句式、辭彙都非常簡單，甚至多有重復，但表達極為清楚，連貫。
[參考譯文]
睡眠
很明白，人人都需要睡眠。然而，大多數人很少思考他們是如何或為何睡眠的。我們知道隻要睡好了，就覺得休息好了。如果睡眠不足，就會覺得乏困，易怒。
睡眠好像有兩個目的：身體休息和情緒或心理休息。我們需要讓軀體和大腦都得到休息。為了保持健康，二者都很重要。每天夜裏，我們交替在兩種睡眠之間：積極睡眠和消極睡眠。消極睡眠使我們的身體得到所需的休息，同時為積極睡眠做準備。在積極睡眠中，夢就出現了。
整個晚上，人們在消極睡眠和積極睡眠間變換。大腦得以休息，隨後活躍起來，接著夢便開始。如此迴圈：大腦休息好了，活躍起來，夢又開始了。這樣的迴圈整個晚上要反復好幾次。八小時的睡眠中，人們平均要做上整整一個半小時的夢。