Could sleeping on one’s side reduce risk of Alzheimer’s?

6 Aug

Although the findings are yet to be tested in humans, a study suggests sleeping

posture affects how well the brain clears away waste products. Accumulation of waste

products in the brain is a hallmark of neurodegenerative diseases such as Alzheimer’s and


older woman asleep
The study suggests sleeping on one’s side helps the brain clear waste products more effectively.

In The Journal of Neuroscience, researchers say their findings suggest

sleeping in the lateral, or side position – as compared with sleeping on one’s back or

stomach – appears to help the brain remove waste products more effectively and may thus

reduce the chance of developing neurodegenerative diseases.

Increasingly, research is showing that sleep is important for brain health. Studies

suggest that the brain is better at removing waste products when asleep than awake. And

researchers are also discovering that poor sleep is linked to an increased risk of dementia.

So, if the brain removes waste better during sleep, then does body posture during

sleep make any difference?

This was the question the team, led by Helene Benveniste, a professor of

anesthesiology at Stony Brook University, NY, set out to investigate.

Sleep position affects efficiency of cerebrospinal fluid filtering

For their study, the researchers focused on a complex system in the brain that clears

away harmful substances that threaten to disrupt the normal function of cells and


The system – called the glymphatic pathway – filters cerebrospinal fluid (CSF)

through the brain and exchanges it with interstitial fluid (ISF) to clear waste. The

process resembles the lymphatic system that clears waste from organs in other parts of

the body.

The glymphatic pathway is most efficient during sleep. It clears away potentially

toxic chemicals from the brain – including amyloid beta and tau proteins. Build-up of

these proteins is a known hallmark of Alzheimer’s disease.

The team used dynamic contrast magnetic resonance imaging (MRI) and computer modeling

to measure CSF-ISF exchange in the brains of anesthetized rodents in three positions:

lateral (lying on side), prone (lying on stomach) and supine (lying on back).

The analysis showed consistently that the glymphatic system was most

efficient when the rodents were lying on their side than when they lay on their stomachs

or on their backs.

Prof. Benveniste concludes:

“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.”

Sleeping on one’s side common among humans and most animals

The researchers note with interest that sleeping on one’s side is the most popular

position in humans and most animals, even in the wild.

They suggest their findings lend further support to the idea that sleep serves an

important biological function – to “clean up” the mess that builds up when we are


Co-author Dr. Maiken Nedergaard, who leads a specialist lab for studying brain

function at the University of Rochester, NY, says:

“Our finding brings new insight into this topic by showing it is also

important what position you sleep in.”

Prof. Benveniste cautions that while they believe the same happens in our brains, it needs to be confirmed with further research using MRI or other imaging methods in human subjects.

Meanwhile, Medical News Today recently learned that poor sleep may raise the risk of heart attack and

stroke. This was the conclusion of a study – led by the Russian Academy of Medical

Sciences in Novosibirsk – that followed over 650 men for 14 years and found poor sleep was

linked to double the risk of a heart attack and up to four times the risk of stroke.

Written by Catharine Paddock PhD

Copyright: Medical News Today

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