378. As you sleep you pass through a sequence of sleep states-light sleep, deep sleep and REM(rapid eye movement) sleep -- that repeats approximately every 90 minutes.

英语四级译文:
你睡觉时会经历一系列连续的睡眠阶段—轻度睡眠、深度睡眠以及REM(眼部快速运动)睡眠--这些睡眠阶段大约每90分钟重复一次。

四级词汇讲解:
as此处引导的是时间状语从句，意为“正当……时，随着”。如:
I saw you as I was getting off the bus.我要下公交车的时候看到了你。

pass through意为“经过”。如:
I came to say hello as I was passing through.我路过此地，顺便来跟你打个招呼。
He passed through a difficult period after the divorce.他离婚后经历了一段困难时期。

a sequence of意为“一系列，连续的”。如:
I was confused by a sequence of dance movements.我被连续的舞蹈动作给弄迷糊了。

英语四级考点归纳:
pass的常见短语有:

※ pass away意为“死”，是委婉的表达，相当于中文的“去世”。如:
Her grandfather passed away last year.她的祖父去年去世了。

※ pass sth. down意为“将某物代代相传”。如:
Such knowledge should be passed down over the centuries.这样的知识应该世代相传。

※ pass over sth.意为“忽略某事物，回避某事”。如:
She chose to pass over his rude remarks.她选择对他的粗话不予理会。