How sleep is important to neurodegenerative disease and Ataxia

In 2013, neuroscientists used mouse models to show that during deep Random Eye Movement (REM) sleep, the structure of the brain changes, opens up like a sponge to help clear out metabolites and misfolded proteins. REM is an active, restorative sleep stage characterized by fast eye movements and vivid dreaming. REM makes up about 25% of adult sleep. It plays a vital role in memory consolidation, learning, and emotional regulation. This is the type of sleep that is considered most restorative, as opposed to light napping.  This flow of cerebral spinal fluid (CSF) is part of the glymphatic system.  The glymphatic system is the brain’s waste clearance system. It pumps CSF through brain tissue to wash away metabolic byproducts, such as misfolded disease proteins. This restorative process is heavily dependent on sleep and is up to ten times more active during deep REM sleep as opposed to being awake. The analogy is a busy office building, where the offices are cleaned at night. If that didn’t happen nightly, we would notice quickly. It’s also the reason why your brain can feel toxic trying to work over 24 hours without proper sleep.

Sleep disturbance affects neurodegenerative diseases. The cycle of sleep to the state of REM is controlled by the brain in what is called a circadian rhythm. This rhythm can be thrown off by exposure to light at the wrong times and can have real health effects in people who work late shifts. Circadian rhythm and sleep are affected in ataxia types like Spinocerebellar Ataxia type 3 (SCA3) (Ribeiro et al. 2025), as well as people with other forms of cerebellar ataxia (Sonni et al. 2014).

We refer to SCAs as brain diseases, but the reality is these are whole body disorders, especially for genetic ataxias.  While the brain contains a large number of neurons, so does the gut. These two parts of the body communicate with each other.  This is referred to as the gut-brain axis. Observations in the gut may be telling us what is going wrong in the brain.  Ever avoid a type of food because you got really sick from it once? That’s your gut-brain axis at work.

Recently, a study published in Nature Neuroscience (Garborg et al. 2026), from the Penn State University lab of Patrick Drew, showed that movement of the abdomen during sleep pumps blood to the spinal cord. This pumps CSF around the brain and helps with the flushing out of waste products during that important phase of sleep where the brain opens up to clear the trash. This indicates there is a second step in clearing out the brain of metabolic toxins: First the brain opens up during REM. Then, CSF flushes the brain clear. Lack of REM, and/or lack of abdominal movement in sleep could lead to failure to clear metabolic toxins from the brain. But what causes CSF to flow? It was thought to be related to blood flow from the heart.

Yet, CSF movement is not dependent on heartbeat. Engineers were then called in to simulate this flow of fluid in the brain to understand the mechanics of this pumping action. Again, back to the idea of a brain as a dirty sponge, the easiest way to clean a sponge is to run water through it.

Circadian rhythms can be corrected by drug free methods like chromatherapy, which uses colored light and light timing to reset the correct rhythm. Other approaches such as structured mealtimes and avoiding long naps are also ways to correct sleep rhythms and increase sleep quality.

This work highlights how a healthy gut can support a healthy brain.  Not just correcting sleep disorders can help with neurodegenerative disease, but paying attention to gut health is just as important for MDs to consider when treating a patient with ataxia. This can mean diet, paying attention to the gut microbiome, and prioritizing healthy sleep for those at risk or in the early stages of ataxia.