Quality of sleep indicates the risk of Alzheimer’s disease in older adults, researchers at Washington University in St. Louis have found. When older adults sleep poorly or have less slow-wave sleep, they have higher levels of tau, a toxic brain protein, which is linked to brain damage and cognitive decline. Deep sleep is needed to consolidate memories and wake up feeling refreshed.

However, people with Alzheimer’s wake up tired, their nights become even less refreshing as memory loss, and other symptoms worsen.

‘Measuring how people sleep may be a non-invasive way to screen for Alzheimer’s disease before or just as people begin to develop problems with memory and thinking,’ says lead author Brendan Lucey, assistant professor from the varsity.

The findings published in the journal Science Translational Medicine shows that it was not the total amount of sleep that was linked to tau, but the slow-wave sleep, which reflects the quality of sleep.

The people with increased tau pathology were sleeping more at night and napping more in the day, but they weren’t getting good-quality sleep.

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Researchers believe sleep may be a convenient marker to find people on track to develop Alzheimer’s.