许多人的睡眠时间比他们该睡的要少。而后果就是他们的大脑在为此付出代价。

Nothing feels worse than hearing your alarm clock ring in the morning when your body is screaming for a few extra hours of rest. Given the opportunity, who wouldn’t get more sleep? If I had a choice between a year of unlimited Easter candy and a year of unlimited sleep, I’d say “Bye-bye Cadbury” and “Hello, bed!”

Many people don’t get as much sleep as they should. Since the invention of the light bulb, people sleep about 500 hours per year less than they used to. Whether we’re kept awake by our partner’s snoring or we stay up too late watching TV, we wake up tired, groggy, and cranky. No wonder the coffee industry does so well. Unfortunately, sleep deprivation has some side effects and they can’t all be remedied with a little extra caffeine.

This Is Your Brain on Sleep

While the mechanism of sleep isn’t fully understood yet, doctors and scientists do know that it’s one of our body’s most important processes. Studies show that sleep is important for cellular renewal, helping to replace muscle tissue and dead cells throughout the body. Studies have also shown that sleep is a key time for the brain to process and archive information, including memories. Deep, restorative REM sleep, the kind associated with dreaming, seems to stimulate regions of the brain used in learning.

Every night without adequate rest is like adding to a sleep debt—eventually it will have to be repaid. Even after one sleepless night, we can feel the first effects of sleep deprivation—irritability, memory loss, and drowsiness. Continued sleep deprivation can result in trouble concentrating, blurry vision, impaired judgment, and even more severe mental effects. After just a few days without any sleep, people can begin to experience hallucinations, mania, and nausea. Luckily, if you repay your sleep debt right away, those effects vanish immediately.

Short-Term Side Effects

Sleep deprivation doesn’t just cause mental deficits; our physical abilities are diminished too. Studies have demonstrated that not sleeping can reduce glucose metabolism by as much as 40 percent. We use stored glucose for energy and sleep deprivation can interfere with how the body stores and processes it. Sleep-deprived athletes also experience high levels of cortisol, a stress hormone, as well as lower levels of human growth hormone, which is important for muscle repair. The immune system is also thought to be maintained while asleep; people who don’t get enough sleep tend to be more susceptible to infections and have slower healing times.

Sleep deprivation also has an effect on how the brain stores information. A study at the University of Pennsylvania showed that mice who were taught a task and allowed to sleep afterward remembered what they had learned better than mice that didn’t sleep. Among school-aged children, those who get even one less hour of sleep than their peers have shown to perform more poorly on tests of memory and attention.

Some of the effects of short-term sleep deprivation can be very similar to the effects of being drunk. In 2000, researchers in New Zealand and Australia found that people who drive after being awake for seventeen to nineteen hours performed worse on tests than people with a blood alcohol level of 0.05 percent, almost the legal limit for drunk driving. In fact, the U.S. Department of Transportation reports that as many as 100,000 sleep-related auto accidents occur every year.

One study found that sleep-deprived medical interns working on the night shift were twice as likely to misinterpret patients’ test results. There is even evidence that sleep deprivation may have played a part in some major disasters, including the Exxon Valdez oil spill.

Long-Term Consequences

It’s easy to erase the short-term effects of sleep deprivation—get more sleep. However, when people don’t sleep well for weeks, months, or even years, it can have cumulative effects on their health. Sleep has shown to be important in regulating blood sugar levels and people who don’t sleep can become increasingly resistant to insulin. Long-term insulin resistance puts extra burdens on the pancreas to produce more, and eventually can result in type 2 diabetes.

Recent studies have also linked chronic sleep deprivation to obesity. Sleep has an important effect on the hormones ghrelin and leptin, which control hunger and appetite. When we don’t sleep, these hormones can go out of balance, causing us to eat more than we need. Heart disease, high blood pressure, and depression are other diseases that can result from long-term sleep deprivation.

Get Forty Winks … At Least

It’s common to feel a bit tired in the morning, but how do you know if you’re truly sleep-deprived? Sleep experts say that if you feel groggy or tired during the day, feel the urge to nap, or if you fall asleep within five minutes of lying down, you could possibly be sleep-deprived. Another symptom of severe sleep debt is the occurrence of “microsleeps,” short bursts of sleep that can happen without a person even realizing it.

Although most people think they need to sleep for eight hours a night, the amount actually varies from person to person; some are fine with five, others would do better with ten. If you feel like you need more sleep, simple lifestyle changes can help you get more. Missing a few hours of sleep on occasion isn’t the end of the world, because it’s easy to make up the sleep with no lasting side effects. Many people are psychologically adjusted to constantly feeling tired, and in the short-term, their bodies may be able to adjust too. But the long-term consequences of sleep deprivation should be enough to convince anyone to hit the sack.

没有比早晨你的起床闹钟铃响了而你的身体却还在渴求再多几个钟头休息更让人感觉糟糕的了。只要有机会，谁不会想再多睡会儿呢？如果能让我在一年内无限制地享用复活节糖果和一年内能享受无限制的睡眠之间做选择的话，我会说“再见，吉百利糖果”和“你好，床榻！”的。

许多人没有得到他们应该得到的足够的睡眠。自从灯泡发明之后，人们比没有灯泡的时代平均一年少睡500个小时的觉。不管原因是我们被伴侣的鼾声折磨得睡不着还是因为看电视看得太晚，我们醒来后感觉疲惫不堪、昏昏沉沉、脾气暴躁。无怪乎咖啡行业生意如此兴隆。不幸的是，睡眠的被剥夺有一些副作用不是单靠一点额外的咖啡因就能矫治的。

这是你的大脑在休息

虽然迄今为止关于睡眠的机制还没有完全被了解，医生们和科学家们已经确知它是我们身体最重要的生理过程之一。研究表明睡眠对细胞更新至关重要，帮助在全身范围内替换老的肌肉纤维和死细胞。研究也表明睡眠时间是大脑处理和存储信息包括记忆的重要时段。深层的,恢复性的眼球快速运动（REM）睡眠,也就是与做梦相关的那种睡眠，似乎能刺激大脑中用于学习的那些部分。

每个晚上没有足够的休息就像让睡眠欠上了债--而债最终是得还的。哪怕只是一夜不眠，我们都能感到睡眠被剥夺的最初的症状—易怒、记忆丧失和昏昏欲睡。持续的睡眠剥夺能导致注意力难以集中、视野模糊、缺乏判断力，甚至是更严重的脑部症状。只要一连几天不睡觉，人会开始出现幻觉、躁狂症和恶心。幸运的是，如果你马上偿还睡眠欠账，这些症状马上就会消失。

短期副作用

睡眠剥夺不仅仅导致脑部功能缺失，它也会减弱我们的身体行动能力。研究显示不睡觉会降低葡萄糖代谢达40%之多。我们的身体储存葡萄糖为备用能源而睡眠剥夺干扰了身体储存和处理葡萄糖的过程。被剥夺睡眠的运动员体内会经历高水平的氢化可的松--这是一种造成紧张的荷尔蒙，也会出现低水平的人类生长荷尔蒙—该荷尔蒙对肌肉的修复很重要。人的免疫系统也被认为是在睡眠时进行维护的；睡眠不足的人倾向于更易感染疾病而且治愈需更长时间。

睡眠剥夺对大脑存储信息也有影响。一项在宾夕法尼亚大学进行的研究显示那些被教会一项任务并在事后被允许休息的老鼠比那些事后不睡的老鼠对所学任务要记得牢。在学龄儿童中，那些仅仅比他们的同侪少睡一小时的儿童在记忆力和注意力测试中表现得要更差。

短期睡眠剥夺的某些影响与醉酒的后果类似。2000年新西兰和澳大利亚的研究者们对连续17到19小时不睡后的人的汽车驾驶测试结果表明他们比那些血液中酒精浓度达到0.05%的人表现更差，而后者血液中酒精水平几乎就是醉酒驾驶的法律界限。事实上美国交通部报告每年都有多达10万起与睡眠有关的汽车事故发生。

一项研究发现睡眠被剥夺的上晚班的医疗实习生他们误判病人病情测试结果的几率要多一倍。甚至有证据显示对于某些重大灾难的发生睡眠剥夺也在其中扮演了一定的角色，比如埃克森瓦尔德兹号油轮原油泄漏事故。

长期后果

短期睡眠剥夺的副作用是比较容易消除的--补点儿觉就成。然而当人们连着几周，几个月甚至经年睡不好时，这对他们的健康起的副作用就是累积的。睡眠已被证实对规范血糖水平至关重要，而那些不睡觉的人会变得越来越对胰岛素抗拒。长期的对胰岛素抗拒会对胰腺造成额外的负担以迫使它产生更多的胰岛素，而这最终会导致形成II型糖尿病。

最近的研究也把慢性睡眠剥夺与肥胖症联系起来。睡眠对脑肠肽和瘦素这两种荷尔蒙有重要影响，而该两种荷尔蒙控制人的饥饿感和食欲。当我们不睡觉时这些荷尔蒙将会失衡，导致我们吃得比需要的多。心脏病、高血压和忧郁症是其它一些长期的睡眠剥夺可以导致的疾病。

至少闭目养养神吧

早晨起来感到有点疲倦很正常，但是你怎么才能知道你是真的处于睡眠被剥夺的状态呢？睡眠专家们说如果你整天都感觉昏昏沉沉或疲惫不堪，很想要打个盹儿，或者是你躺下来五分钟内就去见了周公，你很可能已经处于睡眠剥夺的状态了。另外一个严重睡眠欠账的并发症现象是“（多次）微睡（microsleeps）”那是多次的短促的睡眠状态，它发生时甚至你都意识不到。

尽管大部分人觉得他们一晚上应该睡八个小时，实际上该睡多久却因人而异；有些人睡五个小时就成，而另一些人就得睡十个小时才够。如果你觉得你得多睡点儿，简单的生活方式的改变能帮你得到它。偶尔缺几个小时觉没什么大不了的，因为很容易事后及时补觉而不会有长期的副作用。许多人对连续感到疲劳在心理上已经做了调适，而在短期内他们的身体也能做出调适。但如果是长期的睡眠剥夺其所带来的后果应该足够能说服任何人赶紧上床睡觉。