填空题


Sleep is part of a person’s daily (11) cycle. There are several different stages of sleep, and they too occur in cycles. If you are an average sleeper, your sleep cycle is as follows. When you fist drift off into slumber, your eyes will roll about a bit, you temperature will drop slightly, your muscles (12) and your breathing will slow and become quite regular. (13) waves slow down a bit too, with the alpha rhythm of rather fast waves pre~ dominating for the first few minutes. This is called stage I sleep. For the next half hour or so, as you relax (14) , you will drift down through stage 2 and stage 3 sleep. The lower your stage of sleep is, (15) your brain waves will be.


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