Why Do We Sleep

这好像是曾经给大家设计过的听写材料

Why Do We Sleep?
Dear A Moment of Science,
Why do we sleep? I know this question has been debated by scientists and philosophers for centuries, but are there any hard and fast answers?

Good question! First, it’s true that scientists have long pondered the mystery of sleep why we do it and why it’s necessary. 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.

But exactly how and why that’s the case is still an open question. Some research, though, may shed a little light on the problem. 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.

More specifically, the study found that sleep sort of changes the brain’s cellular structure. 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.

Other studies have shown that toxic molecules build up in the space between brain cells. Researchers at the University of Rochester found that those molecules vanished faster from the brain when the mice were asleep.

So what does this mean? Well, it could give scientists new ways to study and potentially treat brain disorders like Alzheimer’s by targeting the glymphatic system and helping it better flush away brain toxins.

我们为什么需要睡觉？

亲爱的《科学一科》栏目组：

我们为什么需要睡觉？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？

问得好！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？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。

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。一些研究也许可以稍稍解答这个问题。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。

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。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。

其他的研究表明，有毒分子在脑细胞的间隙中生成。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。

所以，这意味着什么呢？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。

PS：近美国医学界发现了类淋巴系统（glymphatic system）。一些神经胶质细胞会帮助脑脊液蛋白的流动。并形成管层相绕的复杂系统。在管壁之间脑脊液的循环、输送与排放的过程中，使得大脑得以获取养分与排出废物。过去一直机制不明的脑脊液原来正是清理脑部垃圾的排水系统。此系统未来或可在帮助治疗阿兹海默症这类废弃蛋白堆积的病 症上扮演关键角色。阿兹海默症的起因通常被认为是脑部细胞受到名为贝塔淀粉(beta-amyloid)的废弃蛋白质累积而伤害所致。而未来glymphatic system这类清运系统的研究将是研究脑部疾病的重要考量机制。