Sleep Laterally

According to researchers at Stony Brook University, sleeping in the lateral position, as Sleeping in a lateral positonopposed to on one’s back or stomach, could help more effectively remove brain waste and be an important practice to help reduce the chances of developing such neurological diseases as Alzheimer’s and Parkinson’s.  By imaging the brain’s glymphatic pathway with dynamic contrast MRI, Stony Brook University researchers discovered that a lateral sleeping position, the most common among humans and animals, is the best to most efficiently remove waste from the brain.  Brain waste chemicals could contribute to the development of Alzheimer’s disease and other neurological conditions.

Dr. Helene Benveniste, one of the lead researchers in the study, has used dynamic contrast MRI for several years to examine the glymphatic pathway in rodent models.  This method allows researchers to identify and define the glymphatic pathway, where cerebrospinal fluid (CSF) filters through the brain and exchanges with interstitial fluid (ISF) to clear waste, much in the same way the body’s lymphatic system clears waste from organs.  The glymphatic pathway is most efficient during sleep.

In the paper, published in the Journal of Neuroscience, the researchers used a dynamic contrast MRI method along with kinetic modeling to quantify the CSF-ISF exchange rates in anesthetized rodents’ brains in three positions: lateral, prone and supine.  The analysis has showed that glymphatic transport was most efficient in the lateral position when compared to the supine or prone positions.  The researchers have therefore proposed that the body posture and sleep quality should be considered when standardizing future diagnostic imaging procedures to assess CSF-ISF transport in humans, meaning that the assessment of the clearance of damaging brain proteins that may contribute to or cause brain diseases.  The researchers developed the safe posture positions for the experiments.  To validate the MRI data and assess the influence of body posture on the clearance of amyloid from the brains, they used fluorescence microscopy and radioactive tracers.

Despite strides in research, it still isn’t entirely understood why the body “needs” sleep.  Studies like this add further support to the idea that sleep subserves a distinct biological function to “clean up” the mess that accumulates while we’re awake.  Many types of dementia have been 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.

The researchers have cautioned that while the research team speculates the human glymphatic pathway will clear brain waste most efficiently when sleeping in the lateral position, testing with MRI or other imaging methods on humans is necessary.

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