Sleep On Your Side To Best Kick Out Your Brain's Waste

If you want to develop an effective 'drainage system' for your brain, then you need to sleep in the lateral, or side position, not on your back or stomach. The posture will not only improve your brain's 'cleanliness', but also bring down the possibility of developing Alzheimer's, Parkinson's and other neurological diseases, say researchers at Stony Brook University., according to sciencedaily.

With the help of "contrast magnetic resonance imaging" (MRI) the scientists imaged the brain's glymphatic pathway. This is a complex system that removes wastes as well as additional harmful chemical solutes from the brain, say Stony Brook University researchers Hedok Lee, PhD, Helene Benveniste, MD, PhD, and colleagues.

In humans and many animals, the lateral sleeping position is also the most used position. The buildup of most of the brain's waste chemicals might lead to the development of Alzheimer's disease as well as related neurological conditions.

Their finding is published in the Journal of Neuroscience.

Rodent models were used by Dr. Benveniste, Principal Investigator and a Professor in the Departments of Anesthesiology and Radiology at Stony Brook University School of Medicine, who leveraged the dynamic contrast MRI for several years to examine the glymphatic pathway. It was a method that helped researchers to identify and define the route in which cerebrospinal fluid (CSF) was filtered through the brain and was exchanged with interstitial fluid (ISF) to clear wastes, just like the body's lymphatic system cleared some materials from organs.

Only during sleep the glymphatic route proved to be the most effective.

In the paper, "The Effect of Body Posture on Brain Glymphatic Transport," Dr. Benveniste and colleagues employed a dynamic contrast MRI method along with kinetic modeling to explore three different sides used by them---lateral (side), prone (down), and supine (up).

"The analysis showed us consistently that glymphatic transport was most efficient in the lateral position when compared to the supine or prone positions," said Dr. Benveniste. "Because of this finding, we propose that the body posture and sleep quality should be considered when standardizing future diagnostic imaging procedures to assess CSF-ISF transport in humans and therefore the assessment of the clearance of damaging brain proteins that may contribute to or cause brain diseases."

Dr. Nedergaard, a colleague at the University of Rochester said: "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.

"The study therefore adds further support to the concept that sleep subserves a distinct biological function of sleep and that is to 'clean up' the mess that accumulates while we are awake. Many types of dementia are linked to sleep disturbances, including difficulties in falling asleep. It is increasing acknowledged that these sleep disturbances may accelerate memory loss in Alzheimer's disease. Our finding brings new insight into this topic by showing it is also important what position you sleep in," she added.