How the brain cleans itself every night to help reduce the risk of neurodegenerative diseases
Doctors will often feel your neck for swollen lymph nodes when you are sick. Lymph nodes, vessels, ducts, tissues, and organs are all a part of your lymphatic system. This system moves lymph throughout your body and is a key part of your immune system. The lymphatic system cleans tissues of potentially harmful substances. [1]. The lymphatic system isn't present in the central nervous system (CNS) despite the fact that the brain is one of the most metabolically active organs in the body. How the brain cleaned itself was a question among scientists until 2013 when it was discovered that the brain has its own "lymphatic system", termed the glymphatic system [2].
The Glymphatic System:
The brain is a very active organ, meaning many biochemical processes occur that, like all biochemical processes in the body, create natural waste products. These waste products can be harmful to the body, such as β-amyloid and α-synuclein [2, 3]. The body has a built in system to protect the brain from these damaging waste products -- the glymphatic system [1].
The glymphatic system moves cerebrospinal fluid (CSF) and interstitial fluid (ISF) throughout the brain and exchanges "cellular garbage" for nourishing compounds such as glucose, amino acids, growth factors, and more [2, 3]. These fluids essentially "wash" the brain to removes harmful substances. The glymphatic system ultimately empties into the body's lymphatic system where it can be further processed and/or removed from the body [4].
When Is The Glymphatic System Cleaning:
While the brain/you are awake, lots of neurotoxic waste is produced. When you finally lay your head down and fall asleep, the glymphatic system is able to clean the brain of this neurotoxic waste [5]. Some researchers are even hypothesizing that one of the main functions of sleep is glymphatic cleansing.
"The glymphatic system is mostly inactive when we’re awake, but during sleep it fills channels in our brain (known as interstitial space) with cerebrospinal fluid (CSF)" [4].
Neurodegenerative Diseases and The Glymphatic System:
β-amyloid and α-synuclein are proteins associated with Alzheimers Disease and Parkinson's Disease, respectively [3]. Both are metabolic waste produced in the brain and cleared via the glymphatic system. One study found that β-amyloid was cleared from mice brains via glymphatic pathways [6].
The less time the glymphatic system has to clean the brain, the easier it is for these proteins to build up and the more likely they are to cause Alzheimer's and Parkinson's [3]. This is just one reason why it is so important to get enough sleep.
Support Your Glymphatic System:
Thankfully there are ways to optimize glymphatic functioning to support your brain!
Sleep:
Proper sleep hygiene is essential to ensuring enough quality deep sleep, which is vital for glymphatic functioning [2]. Aim for 7-9 hours a night. Learn more ways to set yourself up for deep sleep. The glymphatic system doesn't have a pump to move the fluid and is influenced by gravity and intracranial pressure. Lee et al. found that sleeping on your side may help move the CSF throughout the brain better than lying on your back or stomach [7].
Exercise:
Exercise and moving your body get your heart pumping and your blood moving to help move the CSF and ISF, influencing glymphatic cleaning of the brain [2]. Specifically, inversions, like in yoga (think downward dog), are a great way to get the CSF moving [8].
Eat Your Omega-3's:
Fish rich in omega-3 polyunsaturated fatty acids supports glymphatic functioning, especially with the clearing of β-amyloid from the brain [9].
Hydrate:
Staying hydrated is important to support the blood flow to the brain. If "we are dehydrated or have consumed too many not-hydrating beverages such as coffee or alcohol, we can have impaired cerebral blood flow [2]." Proper blood flow in the brain is important because it supports the flow of CSF, which is necessary for glymphatic functioning [2].
Reduce Chronic Stress:
Chronic stress can decrease the transport of CSF into and out of the brain, which is harmful to glymphatic functioning. It can also cause the release of corticotrophin-releasing factor (CRF), which increases β-amyloid (related to AD) [10]. Finding ways to reduce stress is a great way to support your glymphatic system. Explore ways to reduce your stress here.
Support Your Digestion:
When your digestion is sluggish, your digestive system will require more energy. This is energy that diverted from glymphatic functioning [2]. Explore ways to support your digestion.
Drink In Moderation:
Lundgaard et al. found that mice “that were exposed to low levels of alcohol consumption, analogous to approximately 2 ½ drinks per day, actually showed less inflammation in the brain and their glymphatic system was more efficient in moving CSF through the brain and removing waste, compared to control mice who were not exposed to alcohol.” [11, 12]. It is important to note that alcohol in larger amounts had detrimental effects. It's all about moderation!
While there are multiple ways to support your glymphatic system, enough quality sleep and exercise have been the two most studied. We can expect more research about the glympatic system, since it was only recently discovered. Staying up-to-date on this research is an empowering way to support our health!
1
University of rochester medical center. Retrieved July 13, 2023. Glymphatic system. https://www.urmc.rochester.edu/labs/nedergaard/projects/glymphatic-system.aspx
2
Euhoy, I. (2019, June 11). 5 ways to boost brain health by optimizing the glymphatic system. Mind body green health. https://www.mindbodygreen.com/articles/how-to-detox-your-brain-by-optimizing-your-glymphatic-system
3
Newman, T. (2019, June 21). How does your brain take out the trash? Medical news today. https://www.medicalnewstoday.com/articles/325493
4
Dessinger, H. 7 ways to support glymphatic flow. Mommy potamus. https://mommypotamus.com/glymphatic-system/
5
Jessen, N. A., Munk, A. S., Lundgaard, I., & Nedergaard, M. (2015). The Glymphatic System: A Beginner's Guide. Neurochemical research, 40(12), 2583–2599. https://doi.org/10.1007/s11064-015-1581-6
6
Iliff JJ, Wang M, Liao Y, et al. A paravascular pathway facilitates CSF flow through the brain parenchyma and the clearance of interstitial solutes, including amyloid β Sci Transl Med. 2012;4:147ra111. doi: 10.1126/scitranslmed.3003748.
7
Lee, H., Xie, L., Yu, M., Kang, H., Feng, T., Deane, R., Logan, J., Nedergaard, M., & Benveniste, H. (2015). The Effect of Body Posture on Brain Glymphatic Transport. The Journal of neuroscience : the official journal of the Society for Neuroscience, 35(31), 11034–11044. https://doi.org/10.1523/JNEUROSCI.1625-15.2015
8
Amitrano, O. (Host). (2020, January 8). The stress bible & why you’re exhausted (1) [Audio podcast episode]. What’s the juice. https://blog.organicolivia.com/podcast/episode-01-the-stress-bible-why-youre-exhausted-optimizing-sleep-melatonin-brain-detox-and-your-adrenals/
9
Ren, H., Luo, C., Feng, Y., Yao, X., Shi, Z., Liang, F., Kang, J. X., Wan, J. B., Pei, Z., & Su, H. (2017). Omega-3 polyunsaturated fatty acids promote amyloid-β clearance from the brain through mediating the function of the glymphatic system. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 31(1), 282–293. https://doi.org/10.1096/fj.201600896
10
Reddy, O. C., & van der Werf, Y. D. (2020). The Sleeping Brain: Harnessing the Power of the Glymphatic System through Lifestyle Choices. Brain sciences, 10(11), 868. https://doi.org/10.3390/brainsci10110868
11
Lundgaard, I., Wang, W., Eberhardt, A., Vinitsky, H. S., Reeves, B. C., Peng, S., Lou, N., Hussain, R., & Nedergaard, M. (2018). Beneficial effects of low alcohol exposure, but adverse effects of high alcohol intake on glymphatic function. Scientific reports, 8(1), 2246. https://doi.org/10.1038/s41598-018-20424-y
12
Michaud M. (2018, February 1). In wine, there's heatlh: low levels of alcohol good for the brain. University of rochester medical center. https://www.urmc.rochester.edu/news/story/in-wine-theres-health-low-levels-of-alcohol-good-for-the-brain
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