The Glymphatic System: Your Brain's Nighttime Cleanup Crew
Have you ever wondered why we sleep? When you stop and think about it, it seems strange that nature would favor a state where we're unconscious, motionless, and vulnerable to any passing predator. If biology could function without sleep, there’s no doubt it would. Yet every creature on the planet, from the smallest fruit fly to the largest whale, requires some form of sleep.
The question is why? What could possibly be so important that it's worth the risk?
In recent years, a mountain of scientific research has highlighted just how essential sleep is to our physical and mental health. One of the most interesting lines of research concerns an elegant mechanism which literally cleans up debris that builds up in our brains throughout the day. This system, which turns on while we sleep, is called the glymphatic system.
Relevance to Neurodegenerative Diseases
The glymphatic system was only discovered a few years ago but as more and more research comes out, it appears increasingly relevant to the prevention of neurodegenerative diseases like Alzheimer’s and Parkinson’s. These conditions, which are a terrible, but seemingly inevitable part of aging, share certain common pathophysiological threads, one of which is a buildup of toxic waste products in the brain (e.g. amyloid beta, tau, alpha synuclein).
How The Glymphatic System Works
This leads us back to our question: why do we sleep at night? As it turns out, sleep isn't just a time for dreams and recharging our batteries. It's the brain’s prime time for waste removal, courtesy of our glymphatic system.
Imagine your brain as a bustling metropolis. During the day, it's “all systems go.” Thoughts are flowing, neurons are firing, and information is being processed. But like any big city, all this activity generates waste. And just like in a city, if that waste isn't removed, things start to get messy.
Enter the glymphatic system, our brain's nighttime cleaning crew. This isn't your ordinary cleanup operation. The glymphatic system is a network of tiny, pipe-like structures that piggybacks on the brain's blood vessels. It uses cerebrospinal fluid (CSF), a clear liquid that cushions the brain, to flush away waste products.
Here’s a great video which shows the system in action:
When we sleep, our brain cells shrink, increasing the space between them by up to 60%. This extra space allows the CSF to wash through the brain more effectively, carrying away the waste products that have built up during the day. Among these waste products are beta-amyloid, tau, and other toxic proteins associated with Alzheimer's and other diseases.
Sleep and Cognitive Decline
This mechanism offers an elegant account of how a lack of sleep could plausibly cause cognitive decline. But do the data support this claim? According to a study performed in 2012, people who slept less than seven hours per night, over decades, were more likely to have accumulations of beta-amyloid and tau than people who sleep more than seven hours per night. Other research does show a significant association between sleep disturbances and Alzheimer’s disease. So far, the mechanism seems to align with the research correlating poor sleep with cognitive decline, and its metabolic correlates.
Understanding the importance of the glymphatic system provides us yet another unambiguous reason to prioritize our sleep, as best we can.
It appears that good sleep is among the longest levers for the prevention of neurodegenerative disease. For now, all we can do is take a proactive stance in optimizing our sleep hygiene, ensuring that we provide the best possible conditions for our brain's own self-cleaning mechanism.
Here's to embracing our nightly slumber for the sake of long-term cognitive health.
Sleep Optimization Tools and Tactics
The Wellness Company’s Natural Sleep Formula.
How to engineer the best sleep of your life.
The surprising truth about melatonin, America’s most popular sleep aid.
How sleep improves the health of the immune system.
 Xie L, Kang H, Xu Q, et al. Sleep drives metabolite clearance from the adult brain. Science. 2013;342(6156):373-377.
 Potvin, O., Lorrain, D., Forget, H., Dubé, M., Grenier, S., Préville, M., & Hudon, C. (2012). Sleep quality and 1-year incident cognitive impairment in community-dwelling older adults. Sleep, 35(4), 491-499.
 Wu, H., Dunnett, S., Ho, Y. S., & Chang, R. C. C. (2019). The role of sleep deprivation and circadian rhythm disruption as risk factors of Alzheimer’s disease. Frontiers in neuroendocrinology, 54, 100764.