A few weeks ago, Andy told me some disappointing news right before bedtime. I didn’t sleep well that night, spending more time trying to process the news than sleeping.
The next morning I awoke tired, with my head feeling heavy and blurred. It reminded me of the newborn years, when the lack of sleep weighed down and when I sometimes felt like my brain was working through sludge.
Turns out there was an actual physiological reason for that sensation in my head—the metabolic trash hadn’t been taken out on those sleepless nights.
It’s also one reason why sleep is so vital for our brain health and worth prioritizing in our family life. Let me explain why.
The Glymphatic System
I learned about this taking-out-the-trash phenomenon back in February. I’d been assigned to write about a study that had been published in the journal Nature. Essentially, the study was on the glymphatic system and the role that neurons play. (Neurons are a type of nerve cell that receive and transmit electrical signals.)
Now, at this point, you may be asking, “Did she mean to write lymphatic system?”
I didn’t, though they do sound similar. And their functions are similar, too—they both help rid the body of waste.
For years, scientists questioned how the brain clears out its own waste because it seemed there weren’t any lymphatic vessels in the brain. The brain is busy, and all that nerve activity creates a lot of metabolic byproducts that can build up quickly in the spaces between the cells. The brain needs to get that out somehow.
Well, in 2012, scientists at the University of Rochester discovered the brain’s pathway for clearing out waste, and they named it the glymphatic system. The name smushes together the words “glial” and “lymphatic.” It’s a lymphatic-like system that’s dependent on a type of nerve cell called glial cell, hence the “g” at the beginning.
The Importance of Fluid Flowing Through the Brain
In a nutshell, the glymphatic system involves a flow of fresh fluid into the brain, through the brain tissue where it intermixes with the fluid located between the cells, and then out of the brain, ultimately draining into lymphatic vessels.
My description greatly simplifies the system, but if you’d like to find out more, Dr. Jeffrey Iliff, one of the scientists who discovered the glymphatic system, talks through his team’s 2012 findings in this 3-minute video.
In the video, Dr. Iliff explains the crux of the glymphatic system, which is that the “continuous flow sweeps along particles that are sitting in between the cells.” It’s taking out the trash!
And we want that trash taken out because not only might it make us feel more clear-headed in the morning, but it might also reduce our chances of neurological disorders, like Alzheimer's disease, down the road.
But here’s the kicker. The glymphatic system is primarily active at a certain time—when we’re asleep.
Why Sleep Matters
In a 2014 TED talk, Dr. Iliff describes what many of us experience: “When you sleep, it clears your mind. And when you don’t sleep, it leaves your mind murky.”
He goes on to explain that the glymphatic system is like you or me with our household chores when life gets hectic. Say it’s one of those nonstop overloaded weeks. We put off our chores because we just don’t have time for them. But come the weekend, we play catch-up, addressing the mess that has built up from Monday through Friday.
Going back to our brains, Dr. Iliff explains that when we’re awake, our brains are busy and don’t have time for a deep clean. But when we go to sleep, our brains switch to clean-up mode. And it’s then, when we are asleep, that our brains get down to work clearing out the metabolic waste that has built up throughout the day.
Dr. Iliff summarizes the process like this: “While our body is still and our mind is off walking in dreams somewhere, the elegant machinery of the brain is hard at work, cleaning and maintaining this unimaginable complex machine.”
And here’s a cool finding from the study published this past February. The researchers showed that during wakefulness, when the glymphatic system isn’t engaged much, there were small, irregular fluctuations in the fluid around the brain cells.
But once sleep set in, neurons in the brain started to synchronize their electrical activity with each other, and this synchronization generated large rhythmic waves that, according to the researchers, were arguably strong enough to carry along metabolic waste. The researchers concluded that “…our findings pinpoint neurons as important drivers of brain clearance…”
I imagine that’s probably enough neuroscience for one sitting. Maybe you’re now wondering if there’s anything we can do to improve our glymphatic system, and the answer is yes. I found a recent scientific review article on lifestyle choices that can impact the glymphatic system. In the Tips section this month, I list a few ideas from that review. We hope it’ll help you and your family.
Based on findings from a 2020 scientific review—“The Sleeping Brain: Harnessing the Power of the Glymphatic System through Lifestyle Choices”—here are some ways you may be able to improve your glymphatic system.
Sleep: Do your best to maximize sleep quality and meet the recommended sleep durations for you and your family members. Here’s a simple list you can check out, which addresses light, temperature, and caffeine. In our home, we use amber hue lights for reading before bedtime.
Sleep on your right side: Research suggests that the glymphatic system is most efficient in this sleep position. It’s likely thanks to gravity and an opening up of the right carotid vein.
Exercise: Research also suggests that physical exercise accelerates glymphatic clearance and reduces the accumulation of amyloid-beta in the brain. (According to Dr. Iliff, amyloid-beta is made and secreted by brain cells all the time. It’s what clogs up the brain in Alzheimer’s disease.)
Other possibilities: Omega-3 consumption and intermittent fasting are also listed in the scientific review for improving the glymphatic system, but I didn’t see any human studies on them when I searched in PubMed. Looks like the research is still preliminary.
Watercolor Painting
Pop out the paint sets, brushes, and watercolor paper for a creative activity with your kids. Focusing on colors and shapes and how the paint bleeds into the water tends to be calming.
Small watercolor paintings can make great thank-you cards for teachers at the end of the school year, too.
Quick Taco Lunch
More of a meal idea than a recipe, this has been my go-to lunch lately because it tastes good, is fast to throw together, and involves minimal prep and clean-up. Here’s what I do:
Warm up the small tortillas in a toaster.
Spread hummus or cheese sauce on the tortillas.
Add chopped-up coleslaw, beans, and a dash of salt.
Thoughts on Memorial Day by Martha K. Baker, this comes from the book Family Celebrations—Poems, Toasts, and Traditions for Every Occasion (editors June Cotner and Nancy Tupper Ling).
“Memorial Day Grace
We have gathered on Memorial Day to remember the soldiers, men and women, who fought for us and lie buried on mountains and islands, on prairies and plains. Long ago, this was “Decoration Day.” Our families cleaned the graves of our families. They trimmed grass and scoured the letters on headstones and planted peonies.
We gather again to decorate the graves with flags, stretched like scrims against the sky, and with our memories and our grief, softened by time.”