Like rain gutters or even public toilets, your brain operates at peak efficiency when there isn't congestive gunk accumulating in its pipes. Only instead of fall leaves or excessive toilet paper, the culprits often found clogging up your intricate neural circuitry are toxic molecules, which gather in the small gaps between brain cells and accumulate over time.
Too much of these waste proteins are, of course, a bad thing, and are thought to be linked to a host of neurodegenerative diseases as we age. A growing body of research points to one especially obstructive protein — beta-amyloid — which is theorized to be at the heart of Alzheimer's. These toxins are somewhat negligible while we're young. But by the time we hit our late 50s, it's akin to a big hair ball clogging up your shower drain.
Certain things may help decongest our neural plumbing: Certain phytonutrients found in berries, for example. But new research points to at least one other way we can keep our brain's pipes squeaky clean and humming at optimum efficiency: Sleep.
Yes, it appears that getting Zs allows cerebrospinal fluid to flow more rapidly throughout our noggins, cleaning out all the wasteful toxic buildup and flushing it away.
"It's like a dishwasher," Dr. Maiken Nedergaard, a professor of neurosurgery at the University of Rochester and an author of the study, tells NPR. For the cleansing flow, the difference between falling asleep or waking is "almost like opening and closing a faucet," says Nedergaard. "It's that dramatic."
So how does this "faucet" work exactly?
Observing the brains of mice, researchers noticed that certain brain cells fluctuate in size depending on the animals' level of consciousness. When they're awake, these brain cells — called glia — are noticeably larger; when the mice were asleep, these same cells shrunk down considerably.
Glia help "control flow throughout the glymphatic system by shrinking or swelling," as Science Daily tells it. So, when the mice were sound asleep (or even in an artificially induced sleep-like state), the shrunken cells allowed cerebrospinal fluid to more effectively flow throughout the brain's crevices.
In fact, researchers note that beta-amyloid seemed to disappear faster in mice that were sleeping, which could have broad-reaching implications for multiple diseases — especially Alzheimer's. "We need sleep," adds Dr. Nedergaard. "It cleans up the brain."