Sleeping less than 6 hours a night in middle age increases the risk of dementia by 30%, according to research

WASHINGTON (CNN) – Calling all those who are sleep deprived: we interrupt your yawn with an important announcement.

Trying to get by with about six hours or less of sleep a night during the work week will prepare your brain for future failures, according to a new study published Tuesday in the journal Nature Communications.

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

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

“Sleep is important for normal brain function and is also believed to be important for clearing toxic proteins that build up in the brain in dementia,” said Tara Spiers-Jones, deputy director of the Center for Discovery Brain Sciences at the University of Technology. University of Edinburgh in Scotland, in a statement. Spiers-Jones was not involved in the investigation.

“What’s the message to all of us? Evidence of sleep disturbance may well before the onset of other clinical evidence of dementia,” said Tom Dening, head of the Center for Dementia at the Institute of Mental Health at the University of Nottingham in the UK. , in a statement.

“However, this study cannot determine cause and effect,” said Denning, who was not involved in the study. “Maybe it’s just a very early sign of dementia to come, but it’s also quite likely that poor sleep isn’t good for the brain and makes it vulnerable to neurodegenerative conditions like Alzheimer’s.”

Chicken or egg?

People with Alzheimer’s disease are known to have sleep problems. In fact, insomnia, nighttime wandering, and daytime sleepiness are common in people with Alzheimer’s disease, 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 previous studies, with research pointing in both directions, said neuroscientist Jeffrey Iliff, a professor of psychiatry and behavioral sciences at the University of Washington School of Medicine.

“In experimental studies there appears to be evidence of both chicken and egg,” Iliff told CNN in a previous interview. “You can drive it both ways.”


Sleep is important for normal brain function and is also believed to be important for clearing toxic proteins that build up from the brain in dementia.

–Tara Spiers-Jones, Center for Discovery Brain Sciences, University of Edinburgh in Scotland


However, some recent studies have examined the damage that sleep deprivation can cause.

People who get less REM or dream phase sleep may be at higher risk of developing dementia, a 2017 study found. REM is the fifth phase of sleep, when the eyes move, the body warms up, breathing and heart rate speed up and the mind dreams.

Healthy middle-aged adults who slept poorly for just one night produced an abundance of beta-amyloid plaques – one hallmark of Alzheimer’s disease, another study published in 2017 revealed. Beta amyloid is a sticky protein compound that disrupts communication between brain cells and eventually kills the cells as it builds up in the brain.

A week of disrupted sleep increased the amount of tau, another protein responsible for the tangles associated with Alzheimer’s disease, frontal lobe dementia and Lewy body disease, the study found.

Yet another 2017 study compared dementia markers in spinal fluid with self-reported sleep problems and found that subjects with sleep problems were more likely to show signs of tau pathology, brain cell damage and inflammation, even when other factors such as depression, body weight, cardiovascular sleep medication.

“Our findings are consistent with the idea that poorer sleep may contribute to the accumulation of Alzheimer’s-related proteins in the brain,” Barbara Bendlin of the Wisconsin Alzheimer’s Disease Research Center told CNN in an earlier interview about the 2017 study.

“The fact that we can find these effects in people who are cognitively healthy and close to middle age suggests that these relationships occur early, which may provide an opportunity to intervene,” Bendlin said.

‘New information’ on connection with sleep deprivation

Because the new study followed a large population over a longer period of time, it adds “ new information to the emerging picture ” about the link between sleep deprivation and dementia, said Elizabeth Coulthard, an associate professor of dementia neurology at the University of Bristol. UK, in a statement.

“This means that at least some of the people who developed dementia probably didn’t already have it at the start of the study when their sleep was first assessed,” said Coulthard, who was not involved in the study.

“It strengthens the evidence that poor sleep in middle age can cause or worsen dementia later in life,” she said.

Right now, science doesn’t have a “ foolproof way to prevent dementia, ” but people can change certain behaviors to reduce their risk, Sara Imarisio, head of strategic initiatives at Alzheimer’s Research UK, said in a statement. Imarisio was not involved in the investigation.

“The best evidence suggests that not smoking, drinking only in moderation, staying mentally and physically active, eating a balanced diet, and controlling cholesterol and blood pressure levels can all help keep our brains healthy as we age.”

How many hours of sleep do you usually get per night?

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