If we think about other sectors of society -- the aged; if you are aged, then your ability to sleep in a single block is somewhat disrupted, and many sleep, again, less than five hours a night. Shift work.
想想社会的其他人群，老年人， 老年人的睡眠 被打断成好几部分， 加起来一晚上睡眠少于五个小时。