Sleep is one of the richest topics in science today: why we need it, why it can be hard to get, and how that affects everything from our athletic performance to our income. Daniel Kripke, co-director of research at the Scripps Clinic Sleep Center in La Jolla, Calif., has looked at the most important question of all. In 2002, he compared death rates among more than 1 million American adults who, as part of a study on cancer prevention, reported their average nightly amount of sleep. To many, his results were surprising, but they've since been corroborated by similar studies in Europe and East Asia. Kripke explains.
Q: How much sleep is ideal?
A: Studies show that people who sleep between 6.5 hr. and 7.5 hr. a night, as they report, live the longest. And people who sleep 8 hr. or more, or less than 6.5 hr., they don't live quite as long. There is just as much risk associated with sleeping too long as with sleeping too short. The big surprise is that long sleep seems to start at 8 hr. Sleeping 8.5 hr. might really be a little worse than sleeping 5 hr.
Morbidity [or sickness] is also "U-shaped" in the sense that both very short sleep and very long sleep are associated with many illnesses—with depression, with obesity—and therefore with heart disease—and so forth. But the [ideal amount of sleep] for different health measures isn't all in the same place. Most of the low points are at 7 or 8 hr., but there are some at 6 hr. and even at 9 hr. I think diabetes is lowest in 7-hr. sleepers [for example]. But these measures aren't as clear as the mortality data.
I think we can speculate [about why people who sleep from 6.5 to 7.5 hr. live longer], but we have to admit that we don't really understand the reasons. We don't really know yet what is cause and what is effect. So we don't know if a short sleeper can live longer by extending their sleep, and we don't know if a long sleeper can live longer by setting the alarm clock a bit earlier. We're hoping to organize tests of those questions.
One of the reasons I like to publicize these facts is that I think we can prevent a lot of insomnia and distress just by telling people that short sleep is O.K. We've all been told you ought to sleep 8 hr., but there was never any evidence. A very common problem we see at sleep clinics is people who spend too long in bed. They think they should sleep 8 or 9 hr., so they spend [that amount of time] in bed, with the result that they have trouble falling asleep and wake up a lot during the night. Oddly enough, a lot of the problem [of insomnia] is lying in bed awake, worrying about it. There have been many controlled studies in the U.S., Great Britain and other parts of Europe that show that an insomnia treatment that involves getting out of bed when you're not sleepy and restricting your time in bed actually helps people to sleep more. They get over their fear of the bed. They get over the worry, and become confident that when they go to bed, they will sleep. So spending less time in bed actually makes sleep better. It is in fact a more powerful and effective long-term treatment for insomnia than sleeping pills.
如今睡眠问题在科学研究里成了一个最丰富的课题：为什么我们需要睡眠，为什么我们睡不着？而且由此会影响到人们的生活工作，甚至会影响你的收入。 Daniel Kripke,（co-director of research at the Scripps Clinic Sleep Center in La Jolla, Calif., ）一直关注着这些最重要的问题。 早在2002年，他就对比了一百万美国成年人的死亡率，这些人作为癌症预防研究的成员向中心报告他们每晚的平均睡眠时间。 对比的结果令人吃惊，但之后欧洲和东亚的相似的这方面的研究证实了他的结果， Kripke说。 Q: 理想的睡眠时间是多久? A: 根据报告研究显示，那些每晚的睡觉时长在 6.5 小时至 7.5 小时之间的人最长寿。 那些睡眠超过8小时或者低于6.5小时的人的寿命会短很多。 睡的太多和睡的太少的人都有很大的健康风险。 最大的惊人之处是所谓的睡眠太久是以8小时为分界线的。 睡8.5小时甚至比只睡5小时还糟糕。 不良的睡眠会会引起很多问题—忧郁症，肥胖病—因此还会引起心脏病—甚至更严重。而且发病率[或健康度]跟据睡眠的时间成“U字形”。 但是这[最佳睡眠时长]会根据不同的健康指标而变化。 大多数人会在7或8小时时达到U型的最低的，但另外一些人却会在6小时，甚至是9小时。 糖尿病患者的最低点会在7小时[样例]。 但这些衡量结果都没有死亡率的数据显得清新。 我认为我们 可以根据数据推断出[睡6.5至7.5小时的人寿命最长]，但我们也必须承认我们真的不知道为什么会这样。 我们真的不知道这些的因果关系。 也就是说我们不清楚如果一个睡眠不足的人是否可以通过增加睡眠时间来活的更久，也不清楚是否一个睡的太多的人是否可以通过把他们的闹钟调早一些就可以更 长寿。 我们期望通过一些团体来试验这些问题。 我一直在宣传这个事实，一个很重要的动因就是想告诉那些失眠症患者少睡一点完全没有问题，以此来减少他们的痛苦。而人们一直在告诉你应该睡8小时，其实 一点证据都没有。 我们在睡眠科门诊部最常见的病人都是睡的太多。 他们认为应该睡8或9个小时，应此一定要花这么久的时间待在床上，这样的结果是很难进入梦乡或者是半夜就醒了。 很有意思的是，很多的有”失眠症“人的问题是由于他们无睡意却躺在床上并担心自己为什么睡不着。 在美国，英国已经欧洲其他很的地方的权威研究都表明：失眠症的治疗方法就是当你睡不着时就不要待在床上，这种限制在床上时间的办法反而你帮助人们获得更 多的睡眠。 他们克服了对床的恐惧。 他们克服了忧虑，当需要睡眠时变得很有信心，这样也就睡着了。 减少在床上的时间确实能提高睡眠质量。 事实表明这是一个比吃安眠药更有效力的长期治疗失眠症的方法。
