How We Sleep May Predict Alzheimer’s Disease

“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. 

“The silver lining here is that there’s something we can do about it,” added Walker. “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.”

Overnight sleep quality of 32 healthy older adults was matched against the buildup of toxic beta-amyloid plaques in their brains which plays a role in the onset and progression of this disease by helping to destroy memory pathways and other brain functions to afflicts upwards of 40 million people around the globe.

Findings show that those who started out experiencing more fragmented sleep and less non-REM slow-wave sleep were the most likely to show an increase in beta-amyloid during the study period. While all participants remained healthy during the study the trajectory of their beta-amyloid growth correlated with baseline sleep quality according to the researchers who were able to predict the increase in these plaques which are thought to mark the beginning of this disease. 

“Rather than waiting for someone to develop dementia many years down the road, we are 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 Winer, the study’s lead author and a Ph.D. student in Walker’s Center for Human Sleep Science at UC Berkeley.

According to the researcher in addition to predicting the time onset is likely to take, their results reinforce the link between poor sleep and Alzheimer’s disease. Previous studies have found that sleep cleanses the brain of beta-amyloid deposits, these findings identify non-REM slow-wave sleep as a possible intervention target against cognitive decline. 

The researchers note that genetic testing can predict an inherent susceptibility and blood testing offers a diagnostic tool, but neither of these can offer a potential for a therapeutic lifestyle intervention that sleep can. 

“If deep, restorative sleep can slow down this disease, we should be making it a major priority,” 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.”

The participants in this sleep study were between the ages of 60-90 who were enrolled in the Berkeley Aging Cohort Study. Each participant spent 8 hours at night sleeping in a lab setting while undergoing polysomnography, which is an array of tests that record brain waves, heart rate, blood oxygen levels and other physiological measures of sleep quality. Over the course of one year participants were evaluated to record the growth rate of beta-amyloid proteins in their brains using positron emission tomography or PET scans to compare their levels to their sleep profile. 

The team focused on brain activity that was present during deep slow-wave sleep, and the researchers also assessed each participant’s sleep efficiency which was defined as being actual time spent sleeping as opposed to lying sleepless while in bed. According to the researchers, their results support their hypothesis of sleep quality being both a biomarker and predictor of this disease to come later on. 

“We know there’s a connection between people’s sleep quality and what’s going on in the brain, in terms of Alzheimer’s disease. But what hasn’t been tested before is whether your sleep right now predicts what’s going to happen to you years later,” Winer said. “And that’s the question we had.”

“Measuring sleep effectively helps us travel into the future and estimate where your amyloid buildup will be,” Walker added.

“Our hope is that if we intervene, then in three or four years the buildup is no longer where we thought it would be because we improved their sleep,” Winer said.

“Indeed, if we can bend the arrow of Alzheimer’s risk downward by improving sleep, it would be a significant and hopeful advance,” Walker concluded.

To help improve your sleep quality:

• Try to maintain a regular sleep schedule of going to bed and waking up at the same time daily
• Wind down before bedtime by avoiding computers, phones, and TV in the final hour before bed
• Keep phones and other digital devices out of the bedroom that may distract you
• Physical exercise during the day helps to promote sleep
• Try to get some exposure to natural sunlight during the day
• In the later parts of the day try to avoid stimulants such as caffeine and alcohol
• If you are having trouble sleeping try to do a relaxing activity such as meditation or reading in dim lighting away from the bedroom, return to the bedroom when you are sleepy
• If you are a heavy snorer and/or feel excessively tired during the day get screened for sleep apnea, and if you are experiencing insomnia consult you doctor or certified medical professional