Sleeping less than 6 hours a night in midlife raises risk of dementia by 30%, study finds

Posted on April 23, 2021

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Source: CNN Health

Calling all those who are sleep-deprived: We interrupt your yawns with an important announcement.

If you're trying to get by on about six hours or less of sleep a night during the work week, you're setting up your brain for future failure, according to a new study published Tuesday in the journal Nature Communications.

After following nearly 8,000 people for 25 years, the study found a higher dementia risk with a "sleep duration of six hours or less at age 50 and 60" as compared to those who slept seven hours a night.

    In addition, persistent short sleep duration between the ages of 50, 60 and 70 was also associated with a "30% increased dementia risk," independent of "sociodemographic, behavioral, cardiometabolic, and mental health factors," including depression, the study said.

      "Sleep is important for normal brain function and is also thought to be important for clearing toxic proteins that build up in dementias from the brain," said Tara Spires-Jones, who is deputy director of the Centre for Discovery Brain Sciences at The University of Edinburgh in Scotland, in a statement. Spires-Jones was not involved in the study.

        "What's the message for us all? Evidence of sleep disturbance can occur a long time before the onset of other clinical evidence of dementia," said Tom Dening, who heads the Centre for Dementia at the Institute of Mental Health at the University of Nottingham in the UK, in a statement.

        "However, this study cannot establish cause and effect," said Denning, who was not involved in the study. "Maybe it is simply a very early sign of the dementia that is to come, but it's also quite likely that poor sleep is not good for the brain and leaves it vulnerable to neurodegenerative conditions like Alzheimer's disease."

        It's well known that people with Alzheimer's suffer sleep issues. In fact, insomnia, nighttime wandering and daytime sleepiness are common for people with Alzheimer's, as well as other cognitive disorders such as Lewy body dementia and frontal lobe dementia.

        But does poor sleep lead to dementia -- and which comes first? This "chicken and egg" question has been explored in prior studies, with research pointing both ways, according to neuroscientist Jeffrey Iliff, a professor of psychiatry and behavioral sciences at the University of Washington School of Medicine.