Dear A Moment of Science,
亲爱的《科学一科》栏目组：
Why do we sleep?
我们为什么需要睡觉？
I know this question has been debated by scientists and philosophers forcenturies, but are there any hard and fast answers?
我知道科学家们和哲学家们就这个问题争论了好几个世纪，但现在有没有确实的，现成的答案？
Good question!
问得好！
First, it's true that scientists have long pondered the mystery of sleep why we do itand why it's necessary.
首先，科学家们长期以来确实在思考睡眠这一谜题，我们为什么需要睡眠，为什么睡眠十分必要？
We know that going without sleep for too long can seriously damage health, so there's good reason to believe that getting enough sleep is important for our well-being.
我们知道长期失眠会严重的危害健康，因此，有必要相信保证睡眠充足对健康很重要。
But exactly how and why that's the case is still an open question.
但失眠为什么会影响健康，又是如何影响的，这个问题仍没有答案。
Some research, though, may shed a little light on the problem.
一些研究也许可以稍稍解答这个问题。
For instance, scientists at the University of Rochester Medical Center in New York did a study with mice, and found that during sleep their brains flush out toxins that accumulate during the day.
比如，纽约罗切斯特大学医学中心的科学家们用老鼠做了一个研究，发现老鼠在睡觉时，他们的大脑会排除白天积累的毒素。
More specifically, the study found that sleep sort of changes the brain's cellular structure.
更确切的说，该研究发现睡眠在某种程度上改变了大脑的细胞结构。
When the mice were asleep or anesthetized, the researchers found that there was more space between their brain cells, allowing a sort of brain plumbing apparatus called the glymphatic system to open wide and allow fluid to flow quickly through the brain.
当老鼠处于睡眠状态或被麻醉是，研究人员发现，他们大脑细胞之间的空间增大了，使被称为脑部类淋巴系统的类似排污管道的器官大大的打开，这样脑脊液就能在大脑中快速的流动。
Other studies have shown that toxic molecules build up in the space between brain cells.
其他的研究表明，有毒分子在脑细胞的间隙中生成。
Researchers at the University of Rochester found that those molecules vanished faster from the brain when the mice were asleep.
罗切斯特大学的研究人员发现，这些分子在老鼠睡觉时从大脑中消失得更快。
So what does this mean?
所以，这意味着什么呢？
Well, it could give scientists new ways to study and potentially treatbrain disorders like Alzheimer's by targeting the glymphatic system and helping it better flush awaybrain toxins.
这意味着通过针对脑部类淋巴系统可以帮助大脑更好的排除脑部毒素，使科学家们有新的方法研究并很有可能治好像老年痴呆症这样的大脑疾病。
