考研優(yōu)美英語作文背誦049
? 考研頻道匯集整理了考研優(yōu)美英語作文背誦總供考生參考，了解更多考研英語、考研政治、考研數(shù)學、考研專業(yè)課復(fù)習資料請登錄考研頻道！
Sleep
Sleep is part of a person's daily activity cycle. There are severaldifferent stages of sleep, and they too occur in cycles. If you are anaverage sleeper, your sleep cycle is as follows. When you first drift off intoslumber, your eyes will roll about a bit, your temperature will dropslightly, your muscles will relax, and your breathing well slow andbecome quite regular. Your brain waves slow down a bit too, with thealpha rhythm of rather fast waves predominating for the first few minutes.This is called stage 1 sleep. For the next half hour or so, as you relaxmore and more, you will drift down through stage 2 and stage 3 sleep. The loweryour stage of sleep, the slower your brain waves will be. Then about 40 to 60minutes after you lose consciousness you will have reached the deepest sleep ofall. Your brain waves will show the large slow waves that are known as the deltarhythm. This is stage 4 sleep.You do not remain at this deep fourth stageall night long, but instead about 80 minutes after you fall into slumber,your brain activity level will increase again slightly. The delta rhythm willdisappear, to be replaced by the activity pattern of brainwaves. Your eyes will begin to dart around under your closed eyelids asif you were looking at something occurring in front of you. This period ofrapid eye movement lasts for some 8 to 15 minutes and is called REM sleep.It is during REM sleep period, your body will soon relax again, your breathingwill grow slow and regular once more, and you will slip gently back fromstage 1 to stage 4 sleep - only to rise once again to the surface of nearconsciousness some 80 minutes later.
全文翻譯：睡眠
睡眠是人每天日?；顒友h(huán)的一部分。人的睡眠分幾個階段，而這些階段也是循環(huán)發(fā)生的。 如果你是一個正常的睡眠者，你的睡眠循環(huán)會這樣進行。在你開始昏昏入睡時，你 的眼睛會滾動幾下，體溫略有下降，肌肉放松，呼吸變得緩慢而有節(jié)奏。除了開始幾分鐘比較快的α節(jié)奏外，腦電波也稍有減緩。這被稱為第一階段睡眠。在隨后約半小時內(nèi)，你 進一步放松，進入第二和第三階段睡眠。 睡眠越深入，腦電波就越緩慢。大約在開始睡眠 后的 40 到 60 分鐘，你將進入沉睡狀態(tài)。 這時的腦電波表現(xiàn)為巨大的緩波，被稱為δ節(jié)奏。 這就是第四階段睡眠。但你并不是整夜都保持這種沉睡狀態(tài)。入睡后約 80 分鐘左右，你 的大腦運動水平會再度略有提高。節(jié)奏消失，并被腦電波的運動圖形取代。 你的眼睛會在閉著的眼瞼下迅速轉(zhuǎn)動，就好象你在看著眼前發(fā)生的什么事情。這種迅速的眼球運動持 續(xù)約 8～15 分鐘，這一階段睡眠被稱之為快速眼動(REM)睡眠。在 REM 睡眠階段，你的肢 體會很快再度放松，呼吸也再次放慢并變得有節(jié)奏，你會輕松地從第一階段滑入第四階段睡 眠-直到大約 80 分鐘后重新接近清醒狀態(tài)。
本文地址：http://www.hengchuai.cn/writing/englishtest/kaoyan/50071.html
