Deep Sleep Protects Against Alzheimer’s, Growing Evidence Shows

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17 Ноя 2020, 20:27

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Researchers are learning that there is a significant relationship between sleep and dementia, particularly Alzheimer’s disease.

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Basak Gurbuz Derma/Getty Images

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In 2013, a landmark study of mice found that their brains switched on a sort of dishwasher during sleep.

«So things like amyloid beta, which are implicated in Alzheimer’s disease, seem to actually be removed more rapidly from the brain when an animal is asleep versus when they’re awake, says Laura Lewis, an assistant professor of biomedical research at Boston University.

In 2019, Lewis led a team that showed how this dishwasher works in people.

«We realized that there’s these waves of fluid flowing into the brain during sleep,» she says. «And it was happening at a much larger and slower scale than anything we’d seen during wakefulness.»

What’s more, each wave of fluid was preceded by a large, slow electrical wave.

So now scientists are looking for ways to induce the slow waves that signal deep sleep. Lewis says it’s easy — in rodents.

«There’s a specific deep brain structure that if you stimulate it, you can cause these sleep-like slow waves in the brain,» she says.

In people, there’s some evidence that rhythmic sounds can increase slow waves.

It’s also possible to boost slow waves by treating certain sleep disorders, says Dr. Yo-El Ju, an associate professor of neurology at Washington University in St. Louis.

Ju was part of a study of people with obstructive sleep apnea, which repeatedly blocks the airway. These patients «seem to have a change in their ability to clear proteins or waste products from their brain,» she says. «And people with sleep apnea are at higher risk for dementia down the line.»

So Ju’s team looked to see what happened after patients had been treated successfully for apnea. The scientists found that treatment resulted in more deep sleep and more beta-amyloid cleared from the brain.

And Ju says there was another effect: Participants’ brains began making less beta amyloid.

«So I don’t know whether it’s that sleep increases clearance or whether sleep decreases the production of waste products,» she says.

Either way, sleep is important to brain health, Ju says – though she admitted to being a bit sleep deprived on the day we spoke.

«My two-year-old decided to sleep in my bed and eat a tortilla and a banana at two in the morning,» she says. «But usually I get a pretty good sleep.»