With more than 5 million Americans living with Alzheimer’s disease, for which there is currently no treatment, UC Berkeley researchers have found that one preventative defense against the disease is deep sleep, according to a study published Sept. 3.

Using positron emission tomography scans, or PET scans, and electroencephalogram, or EEG, sleep recordings, campus neuroscientists and co-authors Matthew Walker and Joseph Winer were able to pinpoint to an extent when Alzheimer’s is most likely to strike in someone’s life.

For the study, researchers recruited participants from the Berkeley Aging Cohort Study, a longitudinal study of healthy aging, according to Winer. Participants then slept overnight in the lab while an EEG recorded their brain activity.

“Each participant also received multiple PET scans, assessing amyloid burden, over the years following the study,” Winer said in an email. “This design allowed us to ask whether sleep quality at baseline was associated with subsequent changes in amyloid plaque levels in the brain.”

PET imaging and sleep EEG recordings allowed the researchers to take a closer look at the proteins involved in Alzheimer’s disease in the brains of healthy individuals, according to Winer. The combination of the two enabled the researchers to assess how sleep physiology differs based on the progression of Alzheimer’s disease years before symptoms begin appearing in individuals.

Participants who experienced less deep restorative sleep and less non-rapid eye movement were more likely to show an increase in beta-amyloid plaques, a main component in the development of Alzheimer’s, according to the study. The beta-amyloid destroys memory pathways and other cognitive functions, which affects more than 40 million people worldwide, according to a Berkeley news article.

“This study is important because it shows that your sleep today may indicate what is going to happen in your brain, in terms of Alzheimer’s disease progression, over the next several years,” Winer said in the email. “As we understand these processes, it may be possible to target sleep as a factor that would delay the progression of the disease.”

Rather than wait for dementia to appear years into someone’s life, this study has allowed researchers to assess how sleep quality now predicts changes in beta-amyloid plaques across longer periods of time, according to Winer. By doing so, scientists can measure how rapidly this toxic protein builds up in the brain over an extended period of time, which can indicate the beginnings of Alzheimer’s disease.

The link between sleep quality and Alzheimer’s reinforced by this study is especially salient now and in the near future as the baby boomer generation starts aging, according to the study.

“Researchers will find ways to prevent the disease in the form of drugs that target early changes in the brain,” Winer said in the email. “For now, we know that lifestyle factors like sleep and exercise are the best ways to maintain brain health into late life.”