October 24, 2024, 11:59 am | Read time: 4 minutes
Exciting results of a study were presented at this year’s Alzheimer’s Association International Conference. Apparently, the risk of neurodegenerative diseases is linked to your sleeping position – one way of lying down is particularly problematic. FITBOOK editor Sophie Brünke presents the study to you.
Everyone has their own preferred sleeping position. Traditionally, a distinction is made between lying on your back, side, and stomach. And each of them has its own specific advantages. For example, lying on your side helps with heartburn, while lying on your back relieves pressure on the spine. However, sleeping on your back is apparently associated with the risk of Alzheimer’s and other neurodegenerative diseases.
Overview
What was previously known about the supine position
Daniel Levendowski, lead author of the study, has already investigated the link between sleep and neurodegenerative diseases in the past. In 2019, he and his team published a study that showed that sleeping in a supine position for more than two hours per night appears to be associated with an increased risk of Alzheimer’s disease and other forms of dementia. A total of 45 people with a diagnosed neurodegenerative disease and 120 control subjects took part at the time.1
Current study follows on from previous work
Based on the findings from 2019, Levendowski and his team wanted to find out more. For their current research, they compared a larger population of subjects with neurodegenerative diseases and people without a known cognitive disorder. The participants included 106 control subjects with an average age of 61.1 years and 164 patients with cognitive impairments, including
- 71 subjects with mild cognitive impairment (MCI), mean age 69.8 years
- 21 subjects with progressive supranuclear palsy (PSP), average age 70.4 years
- 37 subjects with Alzheimer’s disease (AD), average age 72.9 years
- 35 subjects with Parkinson’s spectrum disorder (PSD), average age 68.9 years
The Parkinson’s subjects were further divided into 16 people with Parkinson’s disease, 15 with Lewy body dementia (LBD), and four with Parkinson’s dementia.2
Test subjects wore sleep monitors at night
In order to check which sleeping position(s) the test subjects adopted at night, they were given a sleep monitor that they wore for two nights. This is a device that is worn on the forehead and is able to measure certain sleep biomarkers. These help researchers differentiate the probabilities of certain neurodegenerative disorders. Abnormal lying time on the back was defined as two or more hours.
Alzheimer’s patients were most likely to sleep supine for long periods of time
The study showed that participants with neurodegenerative disorders slept more often than two hours in the supine position compared to the control group. While 44 percent of the control subjects slept on their backs for at least two hours, 61 percent of the MCI group, 69 percent of the LBD group, and 73 percent of the AD group did so. Alzheimer’s was thus most strongly associated with supine sleeping. It was found that Alzheimer’s patients were 3.4 times more likely to have abnormal supine sleep duration compared to healthy controls.
The scientists interpret their results as further evidence of a strong link between supine sleep and neurodegeneration.
Why can sleeping position influence risk?
“Neurotoxins are produced by the use of our brain during the day and are removed from the brain during sleep. The accumulation of unexcreted neurotoxins in our brains begins around midlife and 15 to 20 years before we recognize the first cognitive symptoms associated with neurodegeneration,” Medical News Today quotes study author Levendowski. Furthermore, the scientist explains: “When we sleep on our back, the removal of neurotoxins is less efficient than when we sleep on our side because the venous blood return from the brain to the heart is different. In addition, sleep apnea is more pronounced when sleeping on the back, and the resulting constant interruptions to sleep also contribute to the accumulation of neurotoxins. So our research suggests that inefficient neurotoxin clearance resulting from years of back sleep contributes to neurodegeneration.”
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What happens next?
The research to date shows an association between supine sleep and neurodegenerative diseases. The scientists emphasize that future prospective studies are needed to establish a cause-and-effect relationship.
Study has not yet been published in full
So far, only the study results have been presented at the conference, and the abstract of the study has been published, but the full-length study has not been published in a scientific journal. It is, therefore, not (yet) possible to classify the strengths and weaknesses at this point. Accordingly, the results should be taken with a grain of salt.