A study published in 2013 at the University of Rochester has led to a whole new way of understanding our brain detoxification system, the importance of sleep, and our metabolic homeostasis. We now have a much more thorough, ever expanding view of how the central nervous system (CNS) and thus the brain get rid of metabolic toxins. Previously, it was believed that the cerebrospinal fluid was a sink for extracellular solutes of the CNS and brain, but it was unclear how they were removed because it was thought that the brain did not have a lymphatic system! Now, our understanding of this network of lymphatic vessels continually deepens as more and more studies are published about the glymphatic system, how it works, and why it is important.
Maiken Nedergaard, a Danish neuroscientist created the term by combining the terms “glial cells” and “lymphatic system” to form “glymphatic system”. The glial cells are non-neuronal cells in the nervous system that maintain homeostasis, provide support and structure, and make up the myelin that conducts nerve impulses, and now are known to play an integral role in the glymphatic system function. This function is to act like a lymphatic system for the CNS by removing waste and being a vital component of the immune system.
The glymphatic system is a brain-wide pathway of dural lymphatic vessels found along the blood vessels where cerebrospinal fluid (CSF) and interstitial fluid (ISF) are exchanged. This exchange allows for the clearance of interstitial solutes such as proteins and metabolites from the CNS. It also facilitates brain-wide distribution of important compounds such as glucose, lipids, amino acids, growth factors, and neuromodulators while simultaneously being its site of waste elimination. The glymphatic vessels then transport this waste down through the deep cervical lymph nodes so that it can be excreted from the body.
The glymphatic system functions primarily when we are sleeping and is not engaged when we are awake. Thus, sleep allows for the removal of neurotoxic waste products, including β-amyloid (a protein aggregate found in Alzheimer patients). During sleep, there is a 60% increase in interstitial space that results in an exponential increase in convective exchange of cerebrospinal fluid with interstitial fluid and thus an increase in waste clearance. This fact suggests that perhaps sleep is restorative in part because it allows for the removal of neurotoxic waste products that have accumulated in the CNS, reducing brain inflammation and allowing our whole nervous system to work at its highest potential.
So what does this mean for you? Well, in order to allow for optimal functioning of your glymphatic system to reduce your risk of developing neurodegenerative or other neurologically related disorders, it is imperative that you get a good night’s sleep and allow your glymphatic system go to work!