We're only beginning to understand why we sleep to begin with, but we do know it's essential. Adults need 7 to 8 hours sleep at night, and adolescents need about 10. We grow sleepy due the signals from our body telling our brain we are tired, and signals from the environment telling us it's dark outside. The rise in sleep inducing chemicals, like adenosine and melatonin, send us into a light dose that grows deeper, making our breathing and heart rate slow down and our muscles relax. This non REM sleep is when DNA is repaired and our bodies replenish themselves for the day ahead.
我们也只刚刚才开始了解人类需要睡眠来开始美好的一天，但我们确实知其重要性。成年人每晚需要7至8小时的睡眠，青少年则需要10小时。我们觉得困倦是因为身体向大脑发出了疲倦的信号，也因为外界环境给予了我们天黑的信号。人体则加量分泌能增进睡意的化学物质，如腺苷和褪黑激素，让我们呼吸和心跳频率降低，并使肌肉放松。这种非快速眼动睡眠发生在DNA修复以及身体自我补给时。
In the United States, it's estimated that 30% of adults and 66% of adolescents are regularly sleep-deprived. This isn't just a minor inconvenience. Staying awake can cause serious bodily harm. When we lose sleep, learning, memory, mood, and reaction time are affected. Sleeplessness may also cause inflammation, hallucinations, high blood pressure, and it's even been linked to diabetes and obesity.
调查发现，美国30%的成年人与66%的青少年睡眠不足。可别小看了睡眠不足的后果。一直不睡觉会严重损害身体健康。当我们长时间不睡觉时，学习能力，记忆力，情绪以及反应能力将受到影响。缺乏睡眠也可能导致炎症，幻觉，高血压，甚至糖尿病和肥胖都与睡眠不足有关。

In 2014, a devoted soccer fan died after staying awake for 48hrs to watch the world cup. While his untimely death was due to a stroke, studies show that chronically sleeping fewer than 6 hours a night increasing stroke risk by 4.5 times, compared to those getting consistent 7 to 8 hours of shut-eye.
2014年就有一位足球死忠粉在持续48小时观看世界杯后死亡。虽说他的早逝归根结底是因为中风，但研究表明，夜间睡眠少期少于6小时的人同长期保持7-8小时睡眠的人相比中风的风险会增加4.5倍。
How can sleep deprivation cause such immense suffering? Scientists think the answer lies with the accumulation of waste products in the brain. During our waking hours, our cells are busy using up our day's energy sources, which get broken down into various by-products, including adenosine. As adenosine builds up, it increases the urge to sleep, also known as sleep pressure. In fact, caffeine works by blocking adenosine receptor pathways. Other waste products also build up in the brain, and if they're not cleared away, they collectively overload the brain and our thought to lead to the many negative symptoms of sleep deprivation.
睡眠不足为何如此痛苦呢？科学家们认为其原由为大脑中废物的累积。当我们清醒时，细胞正忙于消耗我们一天中产生的能量，而这些能量的产生会分解出各种副产品，例如腺苷，腺苷的不断产生会使睡眠欲望增加，这样的欲望而被称作睡眠压力。事实上，咖啡因就是通过阻碍腺苷的接收途径来发挥作用的。其他的垃圾产物也会在大脑中堆积，如果他们不被清理掉，大脑将超负荷运转，同时可能会引起许多睡眠不足的不良症状。
So what's happening in our brain when we sleep, to prevent this? Scientists found something called the Glymphatic System, a clean-up mechanism that removes this build up and is much more active when we're asleep. It works by using cerebrospinal fluid to flush away toxic by-products that accumulate between cells. Lymphatic vessels, with serve as pathways for immune cells have recently been discovered in the brain, and they may also play a role in clearing out the brain's daily waste products.
所以当我们睡着时，大脑是如何防止这种情况发生的呢？科学家们发现了脑部的类淋巴系统，它是一种可以清除这些垃圾产物的清洁机制，并且在我们睡眠时比较活跃。这种机制利用脑脊髓液将细胞间积累的有毒副产品冲刷掉。最近，研究员发现，在大脑中作为免疫细胞通道的淋巴血管，这些血管可能也起到了清理大脑日常垃圾的作用。
While scientists continue exploring the restorative mechanisms behind sleep, we can be sure that sleeping into slumber is a necessity, if we wanna maintain our health and our sanity.
尽管科学家们还在继续探索人睡着后的修复机制，我们可以肯定的是，如果我们想保持健康的身心，良好的睡眠是非常必要的。