You start off and you go down, down, down, and then you come up, then you get your first REM cycle, again, again, again, again, again, and then you wake up.

从第一阶段开始，到下面的阶段，然后又往上，这时就出现REM睡眠，然后再一次次地循环，直到你睡醒。

耶鲁公开课 - 心理学导论课程节选