我們一生當中的三分之一都是在睡眠中度過的。睡眠如此重要，但是我們對睡眠卻知之甚少，就連科學家也無法完全破解睡眠密碼。當你睡覺的時候，你大概不知道，你的身體依舊忙碌得很呢！那么，你睡著之后身體都在忙些啥呢？

截圖來自Mental Floss網站

1. KEEPING TIME 生物鐘仍在運行

You might be asleep but your hypothalamus is not. It's carefully keeping time for you as part of your circadian rhythm. This not only helps you feel tired so that you go to sleep with the release of melatonin, but a protein called PER is released in the morning that gradually wakes you up, often right before your alarm clock is set to go off.
你也許睡著了，但你的下丘腦沒有睡。它還在一絲不茍地運行著生物鐘。下丘腦會分泌褪黑激素，讓你感到困倦，到了早晨，則會釋放一種名為PER的蛋白質，讓你逐漸蘇醒，通常會在鬧鐘快響的時候把你叫醒。

2. SPOUTING OFF 說夢話

What do you have to say when you're asleep? Sleep-talking or somniloquy can range from random noises to complete sentences. About 5 percent of adults do it (it's slightly more common in children), and it can happen during any stage of sleep. It's most common in men and kids, and can be brought on by fever, sleep deprivation, stress, anxiety, or depression. Don't worry though—there's no evidence people tell their deepest, darkest secrets while asleep. The biggest concern may be that you're keeping your sleep partner awake.
當你沉睡的時候你會說什么呢？夢話可能是語焉不詳的呢喃，也可能是完整的句子。大約5%的成年人會說夢話（小孩說夢話更常見一點），而且在睡眠的任何階段都可能說夢話。男人和孩子說夢話最多見，可能是由發燒、缺覺、壓力、焦慮或抑郁引起。不過不要擔心——沒有證據表明人們會在睡夢中說出自己藏得最深、最陰暗的秘密。最令人煩惱的恐怕是說夢話會把一起睡覺的人吵醒。

3. GRINDING YOUR TEETH 磨牙

Most people grind their teeth while they are asleep, at least sometimes. This habit, called bruxism, can be caused by emotional or psychological states like stress or anxiety, from an abnormal bite (misalignment of your teeth), or even from sleep apnea. Most people are unaware they do this until their dentist notices evidence of unusual wear. If you're damaging your teeth at night, your dentist can give you a mouth guard to prevent it.
多數人在睡覺的時候都會磨牙，至少總有那么幾次。這種磨牙癥可能是由壓力或焦慮等情感或心理狀態引發的，也可能是由牙齒不齊導致的，甚至可能和睡眠呼吸暫停有關。在牙醫發現不尋常的磨損痕跡之前，多數人都沒有意識到自己磨牙。如果你睡覺的時候磨牙，牙醫可以給你一個口腔防護器來預防損傷。

4. CLEARING YOUR BRAIN 清理大腦垃圾

You think you're resting, but your brain is doing some serious housekeeping every single night. While you are asleep your brain clears out some memories and cements and reorganizes others. The brain also physically cleans itself with a flood of cerebrospinal fluid, which removes unnecessary proteins that can act as toxins.
你以為你在休息，但你的大腦每天夜里都在認真地管理“家務”。在你睡覺的時候，你的大腦會清理掉一些記憶，鞏固和整理其他一些記憶。大腦還會用腦脊液自我清潔，去除不必要的有毒蛋白質。

5. GETTING PARALYZED 四肢麻痹

Your muscles are frozen for part of every night. It's actually normal and healthy to be paralyzed during sleep. During rapid eye movement (REM) sleep your brain is busy dreaming, but to protect yourself from responding to the dreams (for example, screaming when something scary happens or waving your arms to push away an oncoming danger in your dream), your body's muscles are paralyzed. It's possible to actually wake up during the tail end of this cycle and be awake but unable to move, which can be upsetting or even terrifying. It's also relatively common, having occurred to about 40 percent of people. These episodes usually pass quickly.
你的肌肉每天晚上都有一段時間會處于麻痹狀態。在睡眠中感到麻痹是正常也是健康的。在快速眼動睡眠期間，你的大腦正忙著做夢，但為了保護自己不對夢中情景做出反應（比如在夢中發生可怕的事情時尖叫，或者揮舞你的手臂趕走夢中即將到來的危險），身體的肌肉會處于麻痹狀態。在夢境臨近結束時醒來，你可能會無法動彈，這可能會讓你困擾甚至驚恐。這也是相對常見的，約有40%的人發生過這種情況。這種麻痹狀態通常很快會過去。

6. DROPPING POUNDS 減肥

You might be conked out at night, but it turns out your body is still working hard. Each night you lose about a pound due to the water vapor you expel while breathing. You also lose weight since you're expelling carbon atoms with each exhalation. Because of this, the best number on your scale will be first thing in the morning, so take advantage of it!
你可能在晚上就停擺了，但是你的身體卻依然在努力工作。每天晚上，你呼出的水蒸氣都會讓你減重約1磅（約等于454克）。你在每次呼氣時都會排出碳原子，這也會讓你減重。正因如此，早上剛起床就稱體重，會得到最滿意的結果，所以要把握這個機會哦。

英文來源：Mental Floss
翻譯&編輯：丹妮