[解析]
(1)A 考查文章主要内容.根据"There are four levels of sleep,each being a little deeper than the one before"可知,本文讲述的是睡眠的四个深浅程度.所以"Sleep"是最合适的文章标题.故选A.
(2)D 考查词意猜测.根据"Other people believe that drinking warm milk will help make you drowsy.There is also an old suggestion the counting sheep will put you to sleep!"可知,喝牛奶有助于睡眠.所以该词的意思是"有点困意".故选D.
(3)B 考查细节理解.根据"Sleep is necessary for good health"可知,睡眠不足可能会让你身体不好.故选B.
(4)D 考查细节理解.根据"Scientists who study sleep state that when dreaming occurs,your eyeballs begin to move more quickly (Although your eyelids are closed).This stage of sleep is called REM"可知,该阶段是在做梦,并且眼球会转动.故选D.