Sleet1 is part of a person’s daily activity cycle. There are several different stages of sleep, and they too occur in cycles. If you are an average sleeper2, your sleep cycle is as follows. When you fist drift off into slumber3, your eyes will roll about a bit, you temperature will drop slightly, your muscles will relax, and your breathing well slow and become quite regular. Your brain waves slow and become quite regular. Your brain waves slow down a bit too, with the alpha rhythm of rather fast waves 1 sleep. For the next half hour or so, as you relax more and more, you will drift down through stage 2 and stage 3 sleep. The lower your stage of sleep. slower your brain waves will be. Then about 40to 69 minutes after you lose consciousness you will have reached the deepest sleep of all. Your brain will show the large slow waves that are known as the delta4 rhythm. This is stage 4 sleep.
You do not remain at this deep fourth stage all night long, but instead about 80 minutes after you fall into slumber, your brain activity level will increase again slightly. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart5 around under your closed eyelids6 as if you were looking at something occurring in front of you. This period of rapid 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 breathing will slip gently back from stage 1 to stage 4 sleep----only to rise once again to the surface of near consciousness some 80 minutes later.
睡眠
睡眠是人每天日?；顒?dòng)循環(huán)的一部分。人的睡眠分幾個(gè)階段，而這些階段也是循環(huán)發(fā)生的。如果你是一個(gè)正常的睡眠者，你的睡眠循環(huán)會(huì)這樣進(jìn)行。
在你開始昏昏入睡時(shí)，你的眼睛會(huì)滾動(dòng)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(shí)內(nèi)，你進(jìn)一步放松，進(jìn)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(jìn)入沉睡狀態(tài)。這時(shí)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(yùn)動(dòng)水平會(huì)再度略有提高。δ節(jié)奏消失，并被腦電波的運(yùn)動(dòng)圖形取代。你的眼睛會(huì)
在閉著的眼瞼下迅速轉(zhuǎn)動(dòng)，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(yùn)動(dòng)持續(xù)約8～15分鐘，這一階段睡眠被稱之為快速眼動(dòng)(REM)睡眠。
在REM睡眠階段，你的肢體會(huì)很快再度放松，呼吸也再次放慢并變得有節(jié)奏，你會(huì)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)。
1 sleet
n.雨雪；v.下雨雪，下冰雹
參考例句：
There was a great deal of sleet last night.昨夜雨夾雪下得真大。
When winter comes,we get sleet and frost.冬天來到時(shí)我們這兒會(huì)有雨夾雪和霜凍。
2 sleeper
n.睡眠者，臥車，臥鋪
參考例句：
I usually go up to London on the sleeper. 我一般都乘臥車去倫敦。
But first he explained that he was a very heavy sleeper. 但首先他解釋說自己睡覺很沉。
3 slumber
n.睡眠，沉睡狀態(tài)
參考例句：
All the people in the hotels were wrapped in deep slumber.住在各旅館里的人都已進(jìn)入夢(mèng)鄉(xiāng)。
Don't wake him from his slumber because he needs the rest.不要把他從睡眠中喚醒，因?yàn)樗枰菹ⅰ?BR> 4 delta
n.（流的）角洲
參考例句：
He has been to the delta of the Nile.他曾去過尼羅河三角洲。
The Nile divides at its mouth and forms a delta.尼羅河在河口分岔，形成了一個(gè)三角洲。
5 dart
v.猛沖，投擲；n.飛鏢，猛沖
參考例句：
The child made a sudden dart across the road.那小孩突然沖過馬路。
Markov died after being struck by a poison dart.馬爾科夫身中毒鏢而亡。
6 eyelids
n.眼瞼( eyelid的名詞復(fù)數(shù) )；眼睛也不眨一下；不露聲色；面不改色
參考例句：
She was so tired, her eyelids were beginning to droop. 她太疲倦了，眼瞼開始往下垂。
Her eyelids drooped as if she were on the verge of sleep. 她眼瞼低垂好像快要睡著的樣子。 來自《簡(jiǎn)明英漢詞典》
You do not remain at this deep fourth stage all night long, but instead about 80 minutes after you fall into slumber, your brain activity level will increase again slightly. The delta rhythm will disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to dart5 around under your closed eyelids6 as if you were looking at something occurring in front of you. This period of rapid 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 breathing will slip gently back from stage 1 to stage 4 sleep----only to rise once again to the surface of near consciousness some 80 minutes later.
睡眠
睡眠是人每天日?；顒?dòng)循環(huán)的一部分。人的睡眠分幾個(gè)階段，而這些階段也是循環(huán)發(fā)生的。如果你是一個(gè)正常的睡眠者，你的睡眠循環(huán)會(huì)這樣進(jìn)行。
在你開始昏昏入睡時(shí)，你的眼睛會(huì)滾動(dòng)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(shí)內(nèi)，你進(jìn)一步放松，進(jìn)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(jìn)入沉睡狀態(tài)。這時(shí)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(yùn)動(dòng)水平會(huì)再度略有提高。δ節(jié)奏消失，并被腦電波的運(yùn)動(dòng)圖形取代。你的眼睛會(huì)
在閉著的眼瞼下迅速轉(zhuǎn)動(dòng)，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(yùn)動(dòng)持續(xù)約8～15分鐘，這一階段睡眠被稱之為快速眼動(dòng)(REM)睡眠。
在REM睡眠階段，你的肢體會(huì)很快再度放松，呼吸也再次放慢并變得有節(jié)奏，你會(huì)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)。
1 sleet
n.雨雪；v.下雨雪，下冰雹
參考例句：
There was a great deal of sleet last night.昨夜雨夾雪下得真大。
When winter comes,we get sleet and frost.冬天來到時(shí)我們這兒會(huì)有雨夾雪和霜凍。
2 sleeper
n.睡眠者，臥車，臥鋪
參考例句：
I usually go up to London on the sleeper. 我一般都乘臥車去倫敦。
But first he explained that he was a very heavy sleeper. 但首先他解釋說自己睡覺很沉。
3 slumber
n.睡眠，沉睡狀態(tài)
參考例句：
All the people in the hotels were wrapped in deep slumber.住在各旅館里的人都已進(jìn)入夢(mèng)鄉(xiāng)。
Don't wake him from his slumber because he needs the rest.不要把他從睡眠中喚醒，因?yàn)樗枰菹ⅰ?BR> 4 delta
n.（流的）角洲
參考例句：
He has been to the delta of the Nile.他曾去過尼羅河三角洲。
The Nile divides at its mouth and forms a delta.尼羅河在河口分岔，形成了一個(gè)三角洲。
5 dart
v.猛沖，投擲；n.飛鏢，猛沖
參考例句：
The child made a sudden dart across the road.那小孩突然沖過馬路。
Markov died after being struck by a poison dart.馬爾科夫身中毒鏢而亡。
6 eyelids
n.眼瞼( eyelid的名詞復(fù)數(shù) )；眼睛也不眨一下；不露聲色；面不改色
參考例句：
She was so tired, her eyelids were beginning to droop. 她太疲倦了，眼瞼開始往下垂。
Her eyelids drooped as if she were on the verge of sleep. 她眼瞼低垂好像快要睡著的樣子。 來自《簡(jiǎn)明英漢詞典》