为什么睡过头反而更疲倦?

We’ve all been there: It’s been a long week at work, so Friday night, you reward yourself by going to bed early and sleeping in. But when you wake up the next morning (or afternoon), light scathes your eyes, and your limbs feel like they’re filled with sand. Your brain is still lying down and you even have faint headache. If too little sleep is a problem, then why is extra sleep a terrible solution?

我们都有过这种体验：辛劳工作了漫长的一周后，为了好好犒劳自己，周五早早上床，然后睡个自然醒。但是第二天一大早（或者一觉睡到下午）起床的时候，只觉得阳光刺眼，四肢像灌了铅一样。大脑昏昏沉沉，甚至感觉头部隐隐作痛。如果睡得太少是个问题的话，那么为什么睡多了也那么糟糕？

Oversleeping feels so much like a hangover that scientists call it sleep drunkenness. But, unlike the brute force neurological damage caused by alcohol, your misguided attempt to stock up on rest makes you feel sluggish by confusing the part of your brain that controls your body’s daily cycle.

睡过头的感觉跟宿醉之后的感觉极为相似，科学家们称之为“睡醉”。但是，与酒精对神经系统所造成的强烈损伤不同，睡过头这种错误行径所导致的身体行动迟缓，是由于控制身体日常循环的那部分大脑神经被混乱的作息混淆所导致的。

Your internal rhythms are set by your circadian pacemaker, a group of cells clustered in the hypothalamus, a primitive little part of the brain that also controls hunger, thirst, and sweat. Primarily triggered by light signals from your eye, the pacemaker figures out when it’s morning and sends out chemical messages keeping the rest of the cells in your body on the same clock.

身体的内部节奏是提前设定好的，会根据人体内在的生理起搏器、下丘脑部的一系列神经簇还有大脑控制饥饿、口渴和出汗的那一小部分基元来共同作出决定。在昼夜节律系统的生物钟中，生理起搏器主要根据眼部所接收的光线来判断清晨的时间，然后向身体的其他部分发送化学信号告知该时间。

Scientists believe that the pacemaker evolved to tell the cells in our bodies how to regulate their energy on a daily basis. When you sleep too much, you’re throwing off that biological clock, and it starts telling the cells a different story than what they’re actually experiencing, inducing a sense of fatigue. You might be crawling out of bed at 11am, but your cells started using their energy cycle at seven. This is similar to how jet lag works.

科学家们相信：进化后的生理起搏器会告知身体细胞，每日如何管理调节自身能量。如果你睡得过久，就会脱离正常的生物钟，导致生理起搏器对身体细胞发出的讯号与以往实际体验中的不同，包括对疲劳的感觉。你可能在早上11点才从床上爬起来，但是你的身体细胞从早上7点就开始进行能量循环了。这与时差所导致的情况十分相似。