21、第一篇 Sleep Sleep is part of your daily activity cycle, but there are several different types or stages of sleep and they too occur in cycles. If you are an average sl eeper, your sleep cycle will go something like this: When you first drift off into sleep your eyes will roll about a bit, your te mperature will drop slightly, your muscles will relax, and your breathing will s low and b***me quite regular. Your brain waves slow down a bit too. This is cal led Stage 1 sleep. For the next half hour or so, as you relax more and more, you will drift dow n through Stage 2 and Stage 3 sleep. The lower your stage of sleep, the slower y our brain waves will be. Then, about 40-60 minutes after you lose consciousness, you will have reache d the deepest sleep of all. Your brain waves will show the delta rhythm. This I s Stage 4 sleep. You may think that you stay at this deep fourth stage all the rest of the ni ght, but that turns out not to be the case. Instead, about 80 minutes after you fall into sleep your activity cycle will increase slightly. The delta rhythm w ill disappear, to be replaced by the activity pattern of brain waves. Your eyes will begin to move around under your closed eyelids as if you were looking at s omething occurring in front of you. This period of Rapid Eye Movements lasts for some 8-15 minutes and is called REM sleep. During both light and deep sleep, the muscles in your body are relaxed but c apable of movement. However, as you slip into REM sleep, a very odd thing occurs ? Most of the voluntary muscles in your body b***me paralyzed. Although your b rain shows very rapid bursts of neural activity during REM sleep, your body is I ncapable of moving.
The lower the stage of sleep,____
A.the greater the alpha waves will be.
B.the slower the brain waves will appear.
C.activity pattern of the brain.
D.the closer one is to the initial Stage 1 sleep .
22、(同21题)Before one reaches the deepest sleep,_____ A.muscular inhibition occurs .
B.one’s body muscles b***me paralyzed.
C.loss of consciousness has already occurred.
D.one’s eyes begin to move as if looking at something.
23、(同21题)REM sleep is characterized by____
A.a drop in temperature.
B.a loss of consciousness.
C.a lack of body movement.
D.the appearance of data waves.
24、(同21题)Muscular relaxation, a temperature drop, and breath regularity are characteristics of____
A.REM sleep.
B.Stage 1 sleep.
C.delta rhythms.
D.Stage 2 and 3 sleep.
25、(同21题)An increase in the activity cycle indicates____
A.one is waking up.
B.a relaxing of body muscles.
C.an increase in the body’s rhythms.
D.the disappearance of delta rhythm.
