睡眠到底是如何洗去大脑中的毒素的呢

睡眠到底是如何洗去大脑中的毒素的呢

Every night when you sleep, the brain literally washes out toxins built up during the day - but no one's been sure how, until now.

每天晚上，当你睡觉的时候，大脑会洗掉白天产生的毒素——但是直到现在，没有人知道是怎么做到的。

Scientists in the US have discovered a link between slow brain waves during deep sleep and a wave of fluid that washes through, clearing out the mess.

美国科学家发现，深度睡眠时缓慢的脑电波和一波经过大脑的液体之间存在联系。

The discovery could pave the way towards new ways to cure or prevent Alzheimer's disease.

这一发现可能为治疗或预防阿尔茨海默病的新方法铺平道路。

It's been known for a long time that sleep is really important for brain health, study author Laura Lewis told NPR, "but why it is was more mysterious."

研究报告的作者劳拉·刘易斯告诉美国国家公共广播电台(NPR)说:“长期以来，人们都知道睡眠对大脑健康真的很重要，但为什么会这样呢?这个问题更神秘。”

Her team put people into MRI machines while they slept measuring their blood oxygen levels, while EEG caps measured the brain's electrical currents.

她的团队让人们在睡觉时测量血氧水平，同时让他们接受核磁共振成像仪的检测，而脑电图仪则测量大脑的电流。

They found that during deep sleep, the brain's neurons would sync up - turning on and off at the same time. When they were off, the brain doesn't need as much oxygen, so blood flow reduced. In its place, cerebrospinal fluid would wash in.

他们发现，在深度睡眠时，大脑的神经元会同步起来——同时开启、同时关闭。当他们离开的时候，大脑不需要那么多氧气，所以血液流动减少，取而代之的是脑脊液。

Before each wave of fluid, we would actually see a wave of electrical activity in the neurons, Lewis said. "This electrical wave always happens first, and the CSF wave always seems to follow seconds later."

“在每一波液体出现之前，我们实际上会在神经元中看到一波电活动，”刘易斯说。“这种电波总是先出现，脑脊液似乎总是在几秒钟后出现。”

This only happens during deep sleep - not light slumbering or dreaming, and definitely not while people were awake. Previous studies have found a link between not getting enough deep sleep and memory problems.

这种情况只会发生在深度睡眠的时候，而不是在轻度睡眠或做梦的时候，也绝对不会发生在人们清醒的时候。之前的研究已经发现深度睡眠不足和记忆问题之间存在联系。

It's already known that people with Alzheimer's disease have less of these electrophysiological slow waves, so they have smaller and fewer slow waves, said Lewis.

刘易斯说:“我们已经知道，老年痴呆症患者的这种电生理慢波较少，所以他们的慢波更小、更少。”

Alzheimer's has been linked to the build-up of a protein called tau and beta-amyloid. Scientists have struggled to develop drugs that reduce levels of either substance, but this new finding suggests good sleep could be the key.

阿尔茨海默病与一种叫做tau和-淀粉样蛋白的蛋白质的形成有关。科学家们一直在努力研发降低这两种物质水平的药物，但这项新发现表明，良好的睡眠可能是关键。

The findings were published in journal Science on Friday.

研究结果发表在周五的《科学》杂志上。