Scientists Now Know How Sleep Cleans Toxins From the Brain
The synchronized brain waves of non-REM sleep may play a key role in preventing toxins from accumulating in a person’s brain.
One big contribution of the paper is it helps show that the systems Nedergaard has been studying in mice are present and hugely important for humans too. “It’s telling you sleep is not just to relax,” says Nedergaard. “Sleep is actually a very distinct function.” Neurons don’t all turn off at the same time when we’re awake. So brain blood levels don’t drop enough to allow substantial waves of cerebrospinal fluid to circulate around the brain and clear out all the metabolic byproducts that accumulate, like beta amyloid.
VEDANTAM: Iain argues that the right hemisphere of the brain is supposed to play the role of the wise master of our mental kingdom. The left hemisphere is supposed to be the emissary. Iain says we have grown infatuated with the skills of the emissary. We prize the details but scorn the big picture. He makes an analogy about the relationship between the hemispheres.
MCGILCHRIST: I want to emphasize that I resist very strongly the idea that the brain is a computer. It’s just nothing like a computer, actually. But in this one, limited sense, the left hemisphere is a little bit like a very, very smart computer. So you know what the data you’ve collected mean, but you haven’t yet been able to analyze them. You put them into a machine that is just very clever at carrying out a routine. It doesn’t understand. And then it spews out a result, which it also doesn’t understand. But you then take back into the world where the data come from and go, I see.
So that is the relationship. Your left hemisphere is busy processing things to make sure they’re consistent and unpacked, but your right hemisphere’s seeing everything. I am suggesting that we have arrived at a place, not for the first time in the West, where we have slipped into listening only to what it is that the left hemisphere can tell us and discounting what the right hemisphere could have told us.