With some basics behind us, are you ready to hear some of the fascinating things that happen in our bodies when we sleep? The best thing to do is read Matthew Walker’s book Why We Sleep, but I’ll share some of the MANY things I highlighted while reading. All excerpts below are from Walker’s book.
Brainwaves
I find this fascinating. Here’s an example of what a 30-second duration of brainwaves look like while awake, during deep NREM sleep, and during REM sleep. Interestingly, REM and awake waves are almost identical. The “electrical hallmarks of full wakefulness: fast-frequency, chaotic brainwave activity.”
In deep NREM sleep the waves are much slower and predictably rhythmic. Further, these waves are punctuated by sleep spindles – a burst of brainwave activity.
“Sleep spindles occur during both the deep and the lighter stages of NREM sleep, even before the slow, powerful brainwaves of deep sleep start to rise up and dominate. One of their many functions is to operate like nocturnal soldiers who protect sleep by shielding the brain from external noises. The more powerful and frequent an individual’s sleep spindles, the more resilient they are to external noises that would otherwise awaken the sleeper.”
Ready for the coolest part?
“Returning to the slow waves of deep sleep, we have also discovered something fascinating about their site of origin, and how they sweep across the surface of the brain. Place your finger between your eyes, just above “the bridge of your nose. Now slide it up your forehead about two inches. When you go to bed tonight, this is where most of your deep-sleep brainwaves will be generated: right in the middle of your frontal lobes. It is the epicenter, or hot spot, from which most of your deep, slow-wave sleep emerges. However, the waves of deep sleep do not radiate out in perfect circles. Instead, almost all of your deep-sleep brainwaves will travel in one direction: from the front of your brain to the back. They are like the sound waves emitted from a speaker, which predominantly travel in one direction, from the speaker outward (it is always louder in front of a speaker than behind it). And like a speaker broadcasting across a vast expanse, the slow waves that you generate tonight will gradually dissipate in strength as they make their journey to the back of the brain, without rebound or return.”
Ever since reading this I have visualized this phenomenon while lying in bed falling asleep. It reminds me of something from Super Friends, “The Brain Machine.”
The purpose of this period of sleep and incredible brain activity deserves full attention of reading Matt’s book – it is a huge portion of it. It includes things like saving of memories, incredibly important for learning – and forgetting.
This is AMAZING…
Ready for this?
“Around the same time that we were conducting our studies, Dr. Maiken Nedergaard at the University of Rochester made one of the most spectacular discoveries in the field of sleep research in recent decades. Working with mice, Nedergaard found that a kind of sewage network called the glymphatic system exists within the brain. Its name is derived from the body’s equivalent lymphatic system, but it’s composed of cells called glia (from the Greek root word for “glue”).
Glial cells are distributed throughout your entire brain, situated side by side with the neurons that generate the electrical impulses of your brain. Just as the lymphatic system drains contaminants from your body, the glymphatic system collects and removes dangerous metabolic contaminants generated by the hard work performed by neurons in your brain, rather like a support team surrounding an elite athlete.
Although the glymphatic system—the support team—is somewhat active during the day, Nedergaard and her team discovered that it is during sleep that this neural sanitization work kicks into high gear. Associated with the pulsing rhythm of deep NREM sleep comes a ten- to twentyfold increase in effluent expulsion from the brain. In what can be described as a nighttime power cleanse, the purifying work of the glymphatic system is accomplished by cerebrospinal fluid that bathes the brain.
Nedergaard made a second astonishing discovery, which explained why the cerebrospinal fluid is so effective in flushing out metabolic debris at night. The glial cells of the brain were shrinking in size by up to “60 percent during NREM sleep, enlarging the space around the neurons and allowing the cerebrospinal fluid to proficiently clean out the metabolic refuse left by the day’s neural activity. Think of the buildings of a large metropolitan city physically shrinking at night, allowing municipal cleaning crews easy access to pick up garbage strewn in the streets, followed by a good pressure-jet treatment of every nook and cranny. When we wake each morning, our brains can once again function efficiently thanks to this deep cleansing.”
We are literally brainwashing ourselves with every sleep.
Why We Need All Stages of Sleep
“When it comes to information processing, think of the wake state principally as reception (experiencing and constantly learning the world around you), NREM sleep as reflection (storing and strengthening those raw ingredients of new facts and skills), and REM sleep as integration (interconnecting these raw ingredients with each other, with all past experiences, and, in doing so, building an ever more accurate model of how the world works, including innovative insights and problem-solving abilities).”
I’ll go further into REM sleep tomorrow. It deserves an entire post for itself. For know, enjoy these passages as tiny snippets of everything that is happening when we sleep. Like I said a few days ago…
This is Part 4 of my Sleep Week series. If you’re joining today, please go back and read the other posts, too.
If you have landed on this page from an external link, please go HERE to read from the beginning. Otherwise, click on the next title below to continue.
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