Sleeping Too Much Might Be an Early Warning Sign of Dementia, Study Suggests

People who slept more than nine hours a night were six times more likely to develop dementia.

When we daydream about The Retired Life, sleeping in a pretty common theme. But now that bubble has burst — and we're going to be keeping a closer eye on how much time Grandma spends in snoozetown, too: Consistently sleeping more than nine hours a night is linked to an increased risk of dementia, according to new research published in Neurology.

For their February 2017 paper, researchers at the Boston University School of Medicine analyzed data collected from 2,457 adults enrolled in the Framingham Heart Study. Men and women were asked how many hours of sleep they typically get each night, and then were observed for 10 years to determine who developed dementia.

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The researchers ultimately found that participants who slept for more than nine hours each night were six times more likely to develop dementia than those participants who slept for less than nine hours a night. Participants who slept longer were also found to have smaller brain volumes.

But don't start regulating bedtimes just yet: "We're not suggesting you go wake up Grandpa," Sudha Seshadri, MD, senior study author and professor of neurology at Boston University School of Medicine, told the New York Times. "We think this might be a marker for the risk of dementia, not a cause."

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If that's the case and oversleeping is actually a symptom and early indicator of dementia, it could help doctors detect cognitive impairment in patients and make faster diagnoses.

But why would dementia cause people to sleep more? Dr. Seshadri can't say for sure, but he hypothesizes that prolonged sleep might be the brain's way of trying to remove the buildup of beta-amyloid plaques, which are associated with Alzheimer's.

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