People in their 50s and 60s who regularly sleep six hours or less per night are more likely to develop this brain disease than their peers who sleep seven hours or more. This is what a French-British study showed. Sleep duration has already been linked to dementia, but this has not been convincingly proven before. Researchers followed nearly 8,000 people for thirty years, starting in 1985. The study will be published in the journal on Tuesday Nature Communications.
Whitehall II studio
For this study, scientists relied on the Whitehall Study 2, a long-running survey of more than 10,000 British officials. Their health is monitored regularly. For example, nearly 8,000 of them completed questionnaires about their sleep patterns multiple times. Since such a survey can give subjective results, half of that group wore a watch for a period of time recording data about their sleep.
Of the nearly 8,000 people followed, 521 developed dementia, most of them after the age of 70. People who worked an average of seven hours per night were less likely to develop dementia. People who sleep short are often diagnosed with around six hours a night or less. The researchers concluded that: People in their fifties, sixties and seventies who suffer from persistent short sleep are 30% more likely to develop dementia.
Look for risk factors
“This study takes our knowledge of dementia and sleep a step further,” says Jurgen Claassen, a geriatric specialist and researcher at Radboudumc Nijmegen. “It is an affirmation that lack of sleep is an independent risk factor.” Klasen was not involved in the study. The difficult thing about sleep, he says, is that lack of sleep can also be the first manifestation of dementia.
So the open question was: Do you develop dementia due to poor sleep for longer, or is lack of sleep a manifestation of a brain disease? Because of its long duration, Claassen says, this study does short work on the latter hypothesis. A man in his 50s who sleeps briefly as the first sign of dementia is unlikely to develop other symptoms until his 70s.
Klasen himself has researched what short-term sleep deprivation does to accumulate the amyloid beta and tau proteins. Alzheimer’s disease is associated with an excess of these proteins in the cerebrospinal fluid. After one bad night, Klacen found increased amounts of beta-amyloid in the test subjects’ cerebrospinal fluid. After several choppy nights, my tau protein had also risen. The idea is that these proteins are less produced or eliminated during sleep.
Should people be concerned?
Sleeping poorly at night won’t make you dementia, of course, the doctor says, but it can play a role in the long term. Should people in their 50s and 60s who sleep poorly be anxious? Don’t panic, Klasen says, as many other factors also play a role in developing dementia. Scientists believe that about 30 percent of dementia cases can be prevented with lifestyle changes. In other cases, genetic causes and environmental factors play a role.
However, better sleep is important advice, says Klasen, “because it has many proven health effects, for example on cardiovascular disease, which is also a risk factor for developing dementia.” He says it would be good for society to pay more attention to good sleep, for example by paying attention to bio-systems and light pollution. Then, he says, “Thousands of cases of dementia could be prevented.”
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