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The Connection Between Sleep Disruption and Alzheimer's

Written by Alissa Sauer
 about the author
4 minute readLast updated April 10, 2023

A study out of Cambridge suggests that Alzheimer’s disease does not destroy the internal biological clock but that it somehow becomes uncoupled from the sleeping cycle that is present in healthy individuals. Learn more about the connection between sleep disruption and Alzheimer’s disease.

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Sleep disruption in people with Alzheimer’s

Many know that those with Alzheimer’s disease suffer from sleep disruptions, which can be an early symptom of the disease.
The poor biological rhythm associated with Alzheimer’s negatively affects both those with the disease and their caregiver. When those with Alzheimer’s do sleep, sleep is fragmented and leaves sufferers awake at night and tired during the day.
Sleeplessness can also lead to Sundown Syndrome, where the patient experiences agitation and restlessness in the late afternoon and into the evening, which can be particularly tough on caregivers after a long day.

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Until now, the prevailing view was that Alzheimer’s destroyed the biological clock. What we have shown in flies with Alzheimer’s is that the clock is still ticking but is being ignored by other parts of the brain and body that govern behavior. If we can understand this, it could help us develop new therapies to tackle sleep disturbances in people with Alzheimer’s.

Alzheimer’s researchers find ticking internal clock

Cambridge researchers studying sleep disruption began by comparing fruit flies with Alzheimer’s to those with healthy brains.
They then measured the sleeping patterns of the flies using an infrared beam. When the flies were awake, the beam broke, and researchers were able to count and record the breaks in the beam. To test the flies’ biological clocks, the researchers attached a protein that emits light to the protein that helps form the biological clock. The glowing protein allowed researchers to track the internal clock of all the flies.
The researchers found that healthy flies had a “normal” sleep cycle, awake during the day and asleep at night, but those flies with Alzheimer’s fell asleep and woke randomly. However, the sleep patterns of the glowing protein that was attached to the protein in the biological clock was the same in both the healthy flies and the flies with Alzheimer’s, showing that the biological clock still functioned in the flies with Alzheimer’s.
Dr. Damian Crowther of Cambridge’s Department of Genetics is an author of the study. He said this of the findings:

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What sleep disruption and study’s findings mean

Since this research was completed, a more recent study supporting the importance of quality sleep in Alzheimer’s prevention has come to light.
Researchers from the University of California, Berkeley, found evidence that sleep actually cleanses the brain and poor sleep or lack of sleep can build beta-amyloid which attacks the brain. They found that those participants with the highest amounts of beta-amyloid had the poorest quality sleep and performed worst on memory tests, creating a vicious cycle of poor sleep and poor memory with beta amyloid build up.
Similarly, a study led by the Oregon Health and Science University is determining the exact link between Alzheimer’s, beta amyloid build up and sleep.
Co-author of the study and a postdoctoral researcher in the Sleep and Neuroimaging Laboratory, Bryce Mander, is optimistic about the findings. “The data we’ve collected are very suggestive that there’s a link. If we intervene to improve sleep, perhaps we can break that chain,” said Mander.
Researchers plan to expand their study of sleep and beta amyloid build up by tracking a new set of participants over a five year span.
Senior author of the UC Berkeley study, Matthew Walker, summed up the problem, saying:

The more beta-amyloid you have in certain parts of your brain, the less deep sleep you get and, consequently, the worse your memory. Additionally, the less deep sleep you have, the less effective you are at clearing out this bad protein. It’s a vicious cycle.


Meet the Author
Alissa Sauer

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