Deep Sleep May Help Protect the Brain Against Alzheimer’s Onset

September 15, 2020

Sound, restorative sleep may help gird the brain against the ravages of Alzheimer’s disease, scientists report. And the more of it you get, the better.

Researchers at the University of California, Berkeley, report that among healthy older adults, the more soundly they slept, the less buildup in the brain of beta amyloid, a toxic protein that forms the telltale plaques of Alzheimer’s disease. Sound sleep, their research and other studies suggest, acts as a kind of cleaning system, ridding the brain of toxic debris.

“We have found that the sleep you’re having right now is almost like a crystal ball telling you when and how fast Alzheimer’s pathology will develop in your brain,” said Matthew Walker, a UC Berkeley professor of psychology and neuroscience and senior author of the paper, published in the journal Current Biology. “The silver lining here is that there’s something we can do about it. The brain washes itself during deep sleep, and so there may be the chance to turn back the clock by getting more sleep earlier in life.”

For the study, he and colleagues studied the sleep quality of 32 healthy adults, average age 75, in an overnight sleep lab. When we sleep, we move between rapid eye movement, or REM, sleep and non-REM sleep. During REM sleep, your eyes move quickly in different directions and you are more likely to dream. Much of non-REM sleep, or slow wave sleep, is deeper, dreamless sleep.

Over the next four years or so, participants also got regular PET brain scans to look for signs of beta-amyloid buildup. Buildup of beta-amyloid is generally regarded as an indication of increased Alzheimer’s risk when associated with other markers of the disease. Beta-amyloid buildup may be especially important when cognitive deficiencies are present. Importantly, however, a significant number of people have beta-amyloid in the brain without developing serious memory problems or other symptoms of dementia.

All of those in the study remained cognitively healthy during the study period. But at the first PET scan, done about six months into the study, the researchers found that 20 of the 32 participants had evidence of beta-amyloid buildup in the brain, which would be expected given their age.

But as the study continued, the researchers found that the participants who started out experiencing more fragmented sleep and less non-REM slow-wave sleep were most likely to show an increase in beta-amyloid over the course of the study.

“We were able to assess how sleep quality predicts changes in beta-amyloid plaques across multiple timepoints. In doing so, we can measure how quickly this toxic protein accumulates in the brain over time, which can indicate the beginning of Alzheimer’s disease,” said Joseph Winer, the study’s lead author.

The results reinforce the link between poor sleep and Alzheimer’s disease. While previous studies have found that sleep cleanses the brain of beta-amyloid deposits, these new findings identify deep non-REM slow-wave sleep as the target of intervention against cognitive decline.

“If deep, restorative sleep can slow down this disease, we should be making it a major priority,” Dr. Winer said. “And if physicians know about this connection, they can ask their older patients about their sleep quality and suggest sleep as a prevention strategy.”

As many as 20 to 30 percent of the population suffers from insomnia and other sleep disorders, and sleep problems generally increase with advancing age. While people often take drugs like Ambien to help them sleep, it is important to note that when sleep is drug-induced, the sleep architecture — the succession of different sleep phases, including deep non-REM sleep and their respective lengths — does not resemble the natural sleep architecture when drugs are not used. Drugs also can carry serious side effects. Furthermore, some drugs used to promote sleep may actually increase the risk of dementia.

Instead of medications, experts generally recommend cognitive behavioral therapy, which teaches people to challenge negative thoughts at bedtime with positive thoughts that induce relaxation, as the first-line treatment for sleep problems. Cognitive behavioral therapy is much safer than drugs, which should only be used short-term.

Good sleep hygiene is also important. Try to maintain a regular sleep schedule, going to bed and waking up around the same time each day. Limit the bedroom to sleeping, and not watching TV or staring at the computer screen, which can overstimulate the brain. If you can’t get to sleep after 20 minutes or so, try a relaxing bath or reading, then return to bed when you feel sleepy.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Marc Flajolet, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Joseph R. Winer, Bryce A. Mander, Samika Kumar, et al: “Sleep Disturbance Forecasts Beta-Amyloid Accumulation Across Subsequent Years.” Current Biology, September 3, 2020


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