使这个问题进一步复杂化的是，人们感觉愉快的睡眠时间相差很大。
To further confuse the issue, there is an enormous variation in the amount of sleep people feel happy with.
3周后，他们把睡眠时间逐渐缩短到8小时。但是另一件有趣的事发生了。
After three weeks, they gradually reduced their sleep to about eight hours. But another interesting thing happened.
做梦大约占我们睡眠时间的四分之一。
到了20世纪50年代和60年代，人们的睡眠时间大大减少。
By the 1950s and 1960s, that sleep schedule had been reduced dramatically.
这就是研究人员如何使用图表来显示英国青少年每天的睡眠时间。
It is how a researcher used a graphic to show the number of hours spent sleeping by British teenagers each day.
例如，睡眠时间从20世纪50年代的8小时左右下降到近年来的7小时。
For example, sleep duration has declined from some 8 hours in the 1950s to 7 in recent years.
这些结果表明，如果一个企业想要成功，它应该只雇佣每晚睡眠时间少于6小时的人。
These results suggest that if a business wants to prosper, it should hire only people who need less than 6 hours of sleep per night.
在大约15岁左右的时候，由于学校、工作和其他活动的压力，这些男性自愿开始减少夜间睡眠时间。
At about age 15 or so, the men voluntarily began cutting down their nightly sleep time because of pressures from school, work, and other activities.
但在大约15岁左右的时候，由于学校、工作和其他活动的压力，这些男性自愿开始减少夜间睡眠时间。
But at about age 15 or so, the men voluntarily began cutting down their nightly sleep time because of pressures from school, work, and other activities.
从收集到的数据来看，平均而言，导致我们睡眠时间减少的最大元凶的似乎是体育赛事、时节变换和假期。
From data collected, it seems the things that cause us to lose the most sleep, on average, are sporting events, time changes, and holidays.
对你最有帮助的是，对睡眠时间进行安排。
午夜前的睡眠时间被认为是最有帮助的。
The hours of sleep before midnight are thought to be the most helpful.
中学生每天至少应该保证8小时的睡眠时间。
Middle school students should have at least 8 hours' sleep every day.
要想在工作日补上失去的睡眠时间是不可能的。
It is impossible to make up the lost sleeping hours during the workweek.
每个人所需要的睡眠时间各有差异，这往往与年龄有关系。
The amount of sleep each person needs is different, and is often connected to age.
超过40%的初三学生因为学习，每晚的睡眠时间不足8小时。
Over 40% of the Junior 3 have less than eight hours' sleep each night because of study.
根据教育部的规定，小学生每晚应至少有10个小时的睡眠时间。
According to the Ministry of Education, primary school students should get at least 10 hours of sleep a night.
其他一些研究也表明，晚上使用社交媒体的孩子睡得更晚，每周睡眠时间更少，白天更容易犯困。
Some other researches also show that children who use media at night go to bed later, get fewer hours of sleep each week, and become sleepy more easily during the daytime.
随着时间的推移，睡眠不足会让人更加容易生病，尤其是深度睡眠和快速眼动睡眠时间不足时。
Over time, not having enough sleep—especially deep and REM sleep—can cause one to become sick more easily.
大量使用媒体设备会缩短睡眠时间，从而干扰睡眠。
Heavy media use interferes with sleep by reducing sleep duration.
大约40%的美国人在工作日晚上的睡眠时间不足7小时。
Some 40% of Americans get less than 7 hours of shut-eye on week nights.
减少学生晚上的睡眠时间会直接影响他们白天在学校的表现。
Reducing the amount of sleep students get at night has a direct impact on their performance at school during the day.
同样地，美国人在有三天假期的周末晚上睡得晚，早上起得晚，睡眠时间最长。
Similarly, Americans' late nights, late mornings, and longest sleeps fall on three-day weekends.
然而，他们认为那些睡眠时间不超过8小时的学生在回忆旧知识、学习新课程和完成高质量工作方面面临着最大困难。
Yet they rated the students who have received eight hours or less as having the most trouble recalling old material, learning new lessons, and completing high-quality work.
从18世纪和19世纪的日记和其他个人记录中，睡眠科学家已经得出结论——人的平均睡眠时间约为每晚9.5小时。
From diary entries and other personal accounts from the 18th and 19th centuries, sleep scientists have reached the conclusion—that the average person used to sleep about 9.5 hours a night.
他说：“然而，老年人睡眠时间越长，身体越健康。如果他们睡得时间更长一些，大多数老年人会感觉更好、更有精神。”
"More sleep in old age, however, is associated with better health, and most older people would feel better and more alert if they slept for longer periods," he said.
这表明补觉可以弥补部分但不是全部睡眠缺乏造成的损害，考虑到有很多成年人每晚都没有得到他们所需的睡眠时间，这令人鼓舞。
That suggests that catch-up sleep may undo some but not all of the damage that sleep deprivation causes, which is encouraging, given how many adults don't get the hours they need each night.
佐佐木教授发现，正如预期的那样，参与者们在第一晚的睡眠质量不如第二晚，入睡所需时间是第二晚的两倍多，且总体睡眠时间也更少。
Dr. Sasaki found, as expected, the participants slept less well on their first night than they did on their second, taking more than twice as long to fall asleep and sleeping less overall.
异斯皮洛宁和鼠基二肽（MDP）可以促进动物的免疫功能，并延长小鼠和兔子的睡眠时间。
Isoprinosine and muramyl dipeptide (MDP) could promote animal immune function, and prolong the sleeping time of mice and rabbits.
睡眠时间变长，白天容易犯困。
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