Glymphatic System

The glymphatic system is a pathway that clears waste from your brain while you sleep. Like your lymphatic system, it uses fluid to wash away anything your brain doesn’t need. Some types of waste are harmful if they stay in your brain for too long.

The glymphatic system is a relatively recent discovery. Research is ongoing to learn more about how it works, how providers can evaluate it and how it affects certain medical conditions.

What is the main function of the glymphatic system?

The glymphatic system’s main job is to clean your brain by removing waste. Just like other parts of your body, your brain makes waste every day. This system helps clear it out.

Here’s how it works:

1. Your brain cells need fuel (nutrients) to work.
2. After they use that fuel, waste is left behind. That waste has to leave your brain so it doesn’t build up and cause problems.
3. The glymphatic system uses fluid to wash waste out of your brain.

The glymphatic system removes waste like:

• Lactic acid (a type of waste your body makes when it uses energy)
• Proteins like amyloid-β and tau (which can cause problems if they build up)
• Potassium (a mineral that helps your cells but needs to stay balanced)

While it’s cleaning, this system also moves helpful things around your brain, like:

• Amino acids (used to build proteins)
• Sugar (glucose, which gives your brain energy)
• Fats (lipids, which store energy)
• Neurotransmitters (chemicals that help brain cells talk to each other)

How does the glymphatic system work?

This system works by transporting fluid through your brain. There are two types of fluid working together:

• Cerebrospinal fluid (CSF): CSF surrounds and protects your brain and spinal cord.
• Interstitial fluid (ISF): ISF surrounds and protects tissues and cells.

Here’s how researchers describe the process:

1. CSF enters your brain through small spaces between blood vessels (perivascular spaces or Virchow-Robin spaces). The fluid moves as blood vessels expand and contract. This creates pulsations or little waves as your heart beats and when you breathe.
2. CSF meets up with ISF as it travels through brain tissue, with the help of AQP4 water channels. AQP4 is a protein that helps move water through your organs. Waste collection naturally happens as CSF and ISF wash through brain tissue.
3. ISF takes all of the waste it collects and drains it out of your brain through a perivascular space. The waste then enters your lymphatic system in your neck.

What stage of sleep is the glymphatic system most active?

One study found that the glymphatic system works best during stage 3 NREM sleep (also referred to as slow wave sleep or, more commonly, “deep sleep”).

During slow wave sleep (deep sleep), the interstitial space cells get bigger, allowing for more efficient flow of CSF. This makes it easier for the system to remove waste. There’s also a decrease in the neurotransmitter norepinephrine. This relaxes glymphatic vessels, helping fluid exchange.

How does age affect the glymphatic system?

As you get older, this system may not work as well as it used to. Research is ongoing to learn more about why this happens.

One theory is that you may have trouble staying in slow-wave sleep (deep sleep), and a common sleep change associated with aging is a decrease in this kind of sleep. This could be due to disrupted sleep patterns caused by other medical or sleep conditions.

In other words, your glymphatic system spends less time in the “most active” phase of the waste collection process.

What are common conditions associated with the glymphatic system?

Many conditions can affect how your glymphatic system works, especially those that impact your brain and spinal cord (your central nervous system). Glymphatic system dysfunction can also link to many neurologic conditions. Some of the most common conditions include:

• Headache disorders
• Meningitis
• Mood disorders
• Neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease, etc.)
• Normal pressure hydrocephalus
• Sleep disorders
• Stroke
• Traumatic brain injury

What tests check the health of my glymphatic system?

MRI imaging is the most common means of evaluating the glymphatic system. Depending on the symptoms you have, a healthcare provider may order an MRI or offer additional tests to check your general health.

What are common treatments for the glymphatic system?

Treatment to support the glymphatic system may include lifestyle changes, like exercise, improving sleep quality and even hydration.

Providers are still investigating how medications can help.

If certain conditions, like normal pressure hydrocephalus, impact this system, you might need surgery.

Before starting any treatment, talk to your provider about the risks and side effects, so you can decide what’s best for your health.

How can I improve my glymphatic system?

This system works best when you’re sleeping. To help it work better, try building healthy sleep habits and taking care of your body. Here are some tips:

• Go to bed at the same time every night and maintain a regular sleep schedule.
• Get an appropriate amount of sleep nightly. The recommended amount of sleep varies with age, and individual sleep needs may vary.
• Follow a relaxing bedtime routine.
• Turn off screens (like phones or TVs) at least an hour before bed and ideally two to three hours before bedtime.
• Avoid heavy meals or alcohol before sleeping, with the last meal being at least two hours prior to bedtime.
• Participate in physical activities during the day.
• Eat well-balanced meals
• Manage stress

If you need help adjusting your nighttime or daytime routines, or feel that your sleep is disrupted or inadequate, talk to a healthcare provider.