The Glymphatic System: Keeping the Brain Waste-Free

That’s not a typo, you’re reading it right. The glymphatic system does exist, and it’s about time you learn about what it does for your brain and how important sleep is for better brain functioning, too.

What Is the Glymphatic System?

Danish Neuroscientist Maiken Nedergaard discovered the glial cells, which is a waste clearance system in the brain. Since these cells act like lymphatic vessels, she called it the “glymphatic system.”

Before this discovery, scientists thought individual brain cells manage their own metabolic waste accumulating in the brain. (1) Metabolic waste gets stored between the gaps of the brain cells, which is called interstitial space.

The central nervous system (CNS) doesn’t have lymphatic vessels, so it was a question of how to clear the interstitial space. And a lot of metabolic waste builds up quickly since the CNS is always active. Then enter the glymphatic system in the picture, the garbage disposal system of the brain that helps boost the health of brain cells.

The Glial Cells

Glial cells have always been in the brain. However, it was only thought of as support cells because there were no documents proving the number of glial cells compared to the number of neurons in the brain. There are studies, though, that determine the ratio of glial cells to neurons, and apparently, it varies from one species to another.

A type of glial cells called the astroglia or erythrocytes plays a huge role in the proper functioning of the lymphatic system. It works to nourish and protect neurons by insulating them. Some of its functions include detoxification, energy metabolism regulation, metabolic support for neurons, transporting blood-borne material to the neuron, and electrical insulation. (2)

The Cerebrospinal Fluid

Another worth mentioning is the cerebrospinal fluid or CNF. Without it, the brain’s waste clearance system will not work effectively. The CNF is a clear fluid that surrounds the central nervous system. This fluid provides protection, and it moves through the CNS by going through aquaporin-4 channels, which are receptors.

How Does the Glymphatic System Work?

Image from Science Direct

There are three important processes during the waste clearance process. (3) These are:

  1. CSF flows from the basal cisterns, subarachnoid space, and then goes through the periarterial spaces.
  2. The CSF then passes through the aquaporin-4 channels on astroglia and mixes with the brain’s interstitial fluid or ISF.
  3. The mixture of CSF-ISF fluid carries with it the waste material and travels through the perivenous compartment of the large central veins and then exits to the lymphatic vessels.

What Does Sleep Have to Do With It?

Sleep is very important for brain health. This is because glymphatic activity is more active during natural sleep, which means getting proper sleep helps in cleaning the brain.

Scientists were able to deduce this finding based on an experiment with mice. They examined the activity of the glymphatic system in mice that were awake and those that were asleep. The results showed that the distribution of CNF varied greatly. The CNF in the awake mice flowed immediately to the lymphatic vessels, while the CNF in the sleeping mice was able to move through the proper channels properly. (4)

Other Areas to be Explored

Upon the discovery of the glymphatic system, scientists are now finding more and more links to cognitive decline, high blood pressure, diabetes, and how these affect the waste removal of the brain.

One study showed that high blood pressure could impede the functioning of the glymphatic system. When a person has high blood pressure, his blood vessels stiffen. Unfortunately, the glymphatic system relies on the pulsing of the arterial walls to get the trash out.

People with Parkinson’s Disease may also have been affected by the improper functioning of the glymphatic system. According to a study, dopamine pathways in people with Parkinson’s tend to have disrupted sleep-wake cycles, an important factor for the circadian rhythm to work properly. These sleep disturbances are disabling the glymphatic system to clear out the waste, which then contributes to the onset of this disease.

Scientists also discovered a connection between type 2 diabetes and the glymphatic system. In an experience with mice, those with type 2 diabetes had a slower CSF clearance, which was three times slower than the usual. They concluded that the cognitive functions of those with type-2 diabetes may be affected because of this.

Scientists are still exploring the glymphatic system. For us, the takeaway is we should help our body restore and heal itself. Sleep the recommended hours every day and make it a point to prioritise having a good night’s rest. The glymphatic system is always ready to do its job, yet, it needs a hand.



  1. Astroglia | Medical News Today
  2. Asthrocytes | Michigan State University
  3. The Glymphatic System and Waste Clearance with Brain Aging: A Review | Karger
  4. Cleaning the sleeping brain – the potential restorative function of the glymphatic system | Science Direct