Weve all been there： Its 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 theyre 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？

Over sleeping feels so much like a hangover that scientists call it sleep drunkenness. But， unlike the drunkenness damage caused byalcohol， your misguided attempt to stock upon rest makes you feel sluggish by confusing the part of your brain that controls your bodys daily cycle.

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 eyes， the pacemaker figures out when its morning and sends out chemical messages keeping the rest of the cells in your body on the same clock.

Scientists believe that the pacemake revolved to tell the cells in our bodies how toregu late their energy on a daily basis. When you sleep too much， youre throwing off that biological clock， and it starts telling the cells a different story than what theyre actually experiencing， inducing a sense of fatigue. You might be crawling out of bed at 11 a.m.， but your cells started using their energy cycle at seven. This js similar to how jet lag works.

But oversleeping isnt just going to ruinyour Saturday hike. If youre oversleeping onthe regular， you could be putting yourself atrisk for diabetes， heart disease， and obesity. Harvards massive Nurses Health Study found that people who slept 9 to 11 hours a night developed memory problems and were more likely to develop heart disease than people who slept a solid eight（undersleepers are atan even bigger risk）. Other studies have linked oversleeping to diabetes， obesity， and evenearly death， Oversleeping doesnt just happen as amisgui ded attempt at rewarding yourself. The Harvard Nurses Study estimated that chronicover sleeping affects about 4 percent of the population. These are generally people who work odd hours， have an uncomfortable sleepsituation， or a sleeping disorder.

People who work early morning or overnight shifts might be oversleeping to compensate for waking up before the sunrises or going to sleep when its light out. Doctors recommend using dark curtains and artificial lights to straighten things out rather than medication or supplements. Apps likethe University of Michigans Entrain can also help people reset their circadian clock bylogging the amount and type of light they get throughout the day.

When you go to bed， your body cycles between different sleep stages. Your muscles， bones， and other tissues do their repair work during deep sleep， before you enter REM. However， if your bed or bedroom is uncomfortable too hot or cold， messy， orlumpy your body will spend more time in light， superficial sleep. Craving rest， youll sleeplonger.

If everythings just fine with your sleepzone but you still cant get under the eight-hour mark， you might need to go see a doctor. It could be a symptom of narcolepsy， which makes it hard for your body to regulate fatigue and makes you sleep in more. Sleep apnea is a potentially more serious disorder where you stop breathing while you slumber. Its typicallycaused by an obstructed airway， which leads to snoring. However， in a small number of sufferers， the brain simply stops telling the muscles to breathe， starving the brain andeventually forcing a gasping response. Inaddition to all the other terrifying aspects of this disease， its not doing your quality of sleep anyfavors.

No surprise， drugs and alcohol might also be causing you to sleep too much， asdoes being depressed （in fact， oversleeping can contribute to even more depression）. But no matter whats causing it， too much sleep is not good for your long-term health. Ratherthan kicking the can down the road， try getting some equilibrium between your weekend andweekday sleep.

很多人都有过这种经历：经过一周的辛苦工作，好不容易捱到周五，为了犒劳自己早早爬上床，然后睡个懒觉。然而，当你第二天上午（或下午）起床时，却感觉光线刺眼，四肢像灌了铅一般。大脑昏昏沉沉，甚至感觉头部隐隐作痛。如果说睡眠不足是个问题，那么为什么多睡却是个糟糕的解决办法呢？

过度睡眠之后的感觉很像宿醉，科学家把这称之为“睡醉”。但是，与酒精会造成严重的神经损害不同，你囤积睡眠的错误做法搅乱了大脑控制日常身体循环的部分，从而让你感觉无精打采。

你的生理节奏由体内的“昼夜节律控制器”，即一组聚集在下丘脑的细胞群设定。下丘脑是人大脑中原生的一小部分区域，控制人的饥饿感、口渴感和流汗。眼睛接收到光线信号后，“昼夜节律控制器”随之启动并感觉到现在是早上，然后发出化学信号，让你身体其余的细胞保持同样的节奏。

科学家们认为，“昼夜节律控制器”进而指示体内细胞如何每日调节能量。如果你睡得太多，你的生物钟就发生了变化，“昼夜节律控制器”便开始向细胞发出与实际不符的信号，从而引起疲乏感。你可能上午11点才爬下床，但是你体内的细胞在早上7点就开始能量循环了。这与时差反应类似。

然而过度睡眠破坏的可不止你周六的远足。如果你经常性地睡眠过多，就有可能患上糖尿病、心脏病和肥胖症。哈佛大量的护士健康研究数据显示：一晚上睡9到11个小时的人，比起长期睡够8小时的人，更有可能出现记忆力的问题和心脏疾病（睡得更少的人则会有更大的问题）。其他研究表明：睡过头与糖尿病、肥胖症甚至早逝都有所关联。

睡过头可不仅仅是你犒劳自己的错误选择。哈佛护士研究表明：长期睡过头的人群占到总人口比重的4%。这些人一般睡觉时间不规律，入睡环境不舒服，或是有睡眠障碍。

一大早就开始工作的人还有上夜班的人，可能会为了天不亮就起床或者睡得太迟而补觉。医生建议使用深色窗帘或人工照明去解决问题，不要吃药或吃补品。手机应用可以通过记录一天中接收到光线的量和类型，来帮助人们重新设定生物钟——比如密歇根大学的“Entrain”。

当你睡觉时，你的身体会依次经历不同的睡眠阶段。肌肉、骨骼还有其他软组织都会在深度睡眠时进行修复工作，而在快速眼动睡眠阶段则不会。但如果你的床或房间不舒服——太热或太冷、杂乱无章或凹凸不平——你的身体更多处于浅睡眠状态。由于对休息的需求，结果会导致你睡得更久一些。

如果你的睡眠区都没什么问题，但身体还是无法获得8小时的睡眠标识，那么你可能得去看医生了。这可能是嗜睡症的症状，这种病症让你的身体无法调节疲乏感，然后睡得更多。睡眠呼吸暂停综合症是一种更为严重的睡眠障碍，即在睡眠中暂停呼吸。这种情况通常是由于气管内有阻碍所导致的，并导致打鼾。然而，对于一小部分患者而言，大脑只是停止发出让肌肉呼吸的指令，使得大脑自身缺氧，最终导致呼吸困难。这种疾病除了所有骇人听闻的方面以外，对睡眠質量也有所损害。

毫不奇怪，吸毒和喝酒同样会让你睡得过多，抑郁也会（事实上，过度睡眠又会进一步加重抑郁）。但是无论原因为何，过度睡眠对身体的长期健康都是没什么好处的。别再用过度睡眠这种权宜之计了，试着保持工作日与周末的睡眠平衡吧。