Actually, glia and lymphatic equal glymphatic, the name for the system in the brain that Dr. Maiken Nedergaard discovered in 2012. In contrast, we’ve known about the lymphatic system since the seventeenth century. The lymphatic system extends throughout the body. Most of the body’s organs remove dead cells and metabolic waste products using this system. When a physician is palpating your lymph nodes, he or she is checking part of your lymph system.
Glial cells are non-neuronal cells that were discovered in the nineteenth century. They are located in the central and peripheral nervous systems. I know this is a bit technical but just hang in there with me. We know that certain glial cells search for and destroy pathogens and dead neurons. But until just eight years ago, it wasn’t clear to scientists how the brain got rid of its metabolic waste.
The glymphatic system consists of a tunnel around a tunnel. Arteries and arterioles in the pia form the inner tunnel. The pia is the layer of protective tissue just outside the brain itself. Astrocytes are a type of glia cell that look somewhat like a star. They have feet that wrap around all the small blood vessels in the brain to create the outer tunnel. And inside that outer tunnel flows cerebrospinal fluid (CSF).
The CSF flows out of the arteries, flows around the neurons in each part of the brain, and flows into the local venules. Of course, it’s a bit more complicated than that. You can check out online the article The Glymphatic System: A Beginner’s Guide, if you want the details. The flow of this fluid takes the metabolic wastes from the neurons out of the brain. The flow gets rid of pieces of beta-amyloid. These are broken pieces of protein that can build up over time and play a role in Alzheimer’s disease.
Ok, here are the parts I’ve been building up to. Norepinephrine is a neurotransmitter produced in the brain. It wakes us up. It inhibits the production of the CSF. And it causes swelling in cells of the glymphatic system. This swelling minimizes the flow of the CSF when we are awake. Thus, less CSF and less flow of CSF through our brain when we are awake.
However, when we are asleep, our brain cells don’t produce norepinephrine. The swelling in the system goes down. There’s more CSF produced and its flow is much more effective.The CSF takes out with it the neurotoxic waste products from the day. So, when we’re asleep, the whole system is working to detoxify our brain.
So, we need enough sleep for this process to happen to a sufficient degree. How much sleep should we be getting so that our brain can clean itself? The World Health Organization and the National Sleep Foundation both recommend an average of eight hours of sleep per night for adults. On the other hand, too much sleep (more than ten hours per day) isn’t a good for us either, for reasons not relevant to this blog.
I hope the take-home message from this blog is a greater understanding of how important getting a good night’s sleep is. We don’t want those cellular waste products sitting around in our brain and accumulating. To find practical suggestions about getting a good night’s sleep, consult the book “Why We Sleep” by Matthew Walker, Ph.D. And if you’re having problems sleeping, you might consider speaking to a therapist here at STA (call 201-488-6678) who can help you identify and remediate emotional issues that may be interfering with your sleep.