To Avoid Alzheimer's and Parkinson's, Sleep on Your Side

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Humans sleep in all sorts of crazy contortions: flat on their backs, left side, right side, facedown, curled up, sprawled out. And don’t get me started on hammocks. But no matter how you sleep, you’re likely to assume the same favorite position each night. Preference for a sleeping position may be genetic, or based on your subconscious, or a reaction to more mundane realities like body mass and mattress type. A new study from Stony Brook University in New York suggests that to best protect your brain from neurological diseases like Alzheimer’s and Parkinson’s, you should try to sleep in the lateral, or side position.

The research was published in the Journal of Neuroscience and was based on rodent studies. Researchers used MRI imaging to see how the rodent brains’ glymphatic pathway clears waste from the brain. The glymphatic pathway is where the cerebrospinal fluid filters through the brain and meets up with the interstitial fluid to clear waste, such as tau proteins—chemicals that can gunk up brain function.

Snoozing rodents were positioned in three ways: on their side, face down, and belly up. “The analysis showed us consistently that glymphatic transport was most efficient in the lateral position, when compared to the supine or prone positions,” wrote Dr. Helene Benveniste, M.D., Ph.D., the study’s principal investigator and a professor in anesthesiology and radiology at Stony Brook.

“It is interesting that the lateral sleep position is already the most popular in human and most animals – even in the wild – and it appears that we have adapted the lateral sleep position to most efficiently clear our brain of the metabolic waste products that built up while we are awake,” reported her colleague at the University of Rochester, Dr. Maiken Nedergaard. The study supports the idea that sleep “sweeps” the biological and psychological messes that pile up while we are awake.

“Many types of dementia are linked to sleep disturbances, including difficulties in falling asleep. It is increasingly acknowledged that these sleep disturbances may accelerate memory loss in Alzheimer’s disease,” Nedergaard wrote. “Our finding brings new insight into this topic by showing it is also important what position you sleep in.”

The next step would be to do imaging of the glymphatic system in sleeping humans, to see position works best. Until then? Can’t hurt to roll over.