Sleeping on Your Side May Rid Brain of “Waste”

Recent study shows side sleeping may clear the brain of chemical wastes that cause Alzheimer’s, Parkinson’s, and other neurological diseases.

Sleeping on your side (lateral sleep position) may be the best way to clear waste and other harmful chemical solutes from the brain. Researchers say the buildup of brain chemical waste may contribute to the development of Alzheimer’s disease, dementia, and other brain conditions.

The glymphatic pathway is a complex system that clears waste from the brain as cerebrospinal fluid (CSF), the clear liquid found in the brain, filters through the brain and exchanges with interstitial fluid (ISF), the liquid that exists in all other body cells. This exchange allows chemicals and brain waste (like amyloid beta and tau proteins) to be removed before they can build up and lead to Alzheimer’s, Parkinson’s, and other brain diseases. In the study, researchers used dynamic contrast magnetic resonance imaging (MRI) to examine activity in the brain’s glymphatic pathway.

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In the new sleep study, published in the Journal of Neuroscience, researchers examined the CSF-ISF exchange in rodents’ brains in the three different sleep positions: lateral (side), prone (down), and supine (up). Helene Benveniste, principal investigator and professor of anesthesiology and radiology at Stony Brook University School of Medicine, told Futurity that the analysis consistently showed that glymphatic transport was most efficient in the lateral position.

Maiken Nedergaard of the University of Rochester was part of the team who validated the MRI data and assessed the influence of body posture on the clearance of brain waste. She says that, interestingly, the side sleeping position is the most popular among humans and most animals, even in the wild. It appears that we’ve adapted the lateral sleep position to most efficiently clear the waste in our brains that builds up while we’re awake.

The study clearly demonstrates why sleep serves such a distinct and essential biological function. Among rejuvenating our bodies and brains with a number of things we need to survive, it also helps clean up the “mess” that accumulates in our waking brains.

Nedergaard explains the importance of the study’s findings as they highlight how the position you sleep in might affect your brain’s ability to function later in life. While some of you might find sleeping on your stomach or back to be most comfortable, switching to side sleeping may better equip your brain to retain its youthful abilities.