It’s tempting to shortchange ourselves on sleep. There’s so much that needs to get done while we’re awake, and science has never given us a good explanation for why we sleep away one-third of our lives…until now.
Using state-of-the-art imaging technology, researchers have made a startling discovery about the purpose of sleep. It turns out that, as our bodies rest, our brains are busy sweeping away a certain type of toxic detritus that collects during the day—the same type of detritus that’s linked to Alzheimer’s disease and other neurodegenerative disorders. This cleanup process involves changes in the actual cellular structure of the brain—changes we can liken, oddly enough, to a busy movie theater!
Here’s the latest advice on how to keep your brain in top form, plus lots of tips on how to sleep better…
To understand the new research, it helps to think of a movie theater. When a film is showing and the theater is packed, candy wrappers and popcorn and other garbage all fall to the floor. Moviegoers are making a mess, but it would be impossible to clean up while the people are still in their seats. The theater patrons wouldn’t be able to concentrate on the movie…and there wouldn’t be enough room for cleaners to maneuver.
Later, though, after the movie, the people clear out and the seats fold up, and there is much more room. It’s easier to get to the floor beneath to sweep away all the crud that the people left behind.
Researchers from the University of Rochester Medical Center discovered that brains are like movie theaters. When we’re awake, our brains are very active, guiding all our functions. As part of that process, our brains discard toxic proteins (such as the beta amyloid that’s linked to Alzheimer’s) and other by-products—and there’s little opportunity to clean up that debris. However, as the detritus builds up, our brains can’t function as well.
Cool revelation: When we sleep, our brain cells literally shrink—similar to how theater seats fold up—thus enlarging the spaces around the cells. This allows brain fluids to flow more freely, doing their job of picking up the garbage that accumulated during the day and carrying it away.
In most of the human body, the lymphatic system is responsible for collecting and disposing of waste. But the lymphatic system doesn’t make it past the protective blood-brain barrier that closely guards what enters the brain. Instead, cerebrospinal fluid circulates through the brain, picking up the interstitial fluid (fluid between the cells) along with the discarded proteins. This exchange of fluid was named the glymphatic system by the same Rochester researchers after they discovered the intricate network.
For the new study, the researchers used a technique called two-photon imaging and different colored dyes to measure the rate of cerebrospinal fluid flowing through the brains of mice (the mouse brain is remarkably similar to the human brain) when the animals were awake…when they were sleeping naturally…and when they were under general anesthesia.
What the researchers found: The glymphatic system was nearly 10 times more active when the mice were asleep or anesthetized than when they were awake…and the sleeping brains removed significantly more beta amyloid and other debris. This occurred because, when the mice were asleep or anesthetized, their brain cells contracted by more than 60%, creating more space between the cells.
We already know that sufficient sleep helps us think more clearly, do better on tests, make smarter food choices and perhaps keep blood sugar under control. Though it’s too early to say that getting enough sleep helps prevent Alzheimer’s and other neurodegenerative diseases, the new study findings suggest that it might—giving us yet one more reason not to shortchange our slumber time.
Get more sleep: To give your brain the rest it needs, see “Simple Ways to Sleep Better,” above.
