The Link Between Sleep And Alzheimer’s Explained

During slow-wave or deep sleep, the brain is cleared of waste products.

During slow-wave or deep sleep, the brain is cleared of waste products.

A single night of disrupted sleep is enough to increase a brain protein linked to Alzheimer’s, new research shows.

A full week of poor sleep causes increases in another brain protein that is also linked to Alzheimer’s.

The findings may help to explain why poor sleep has been linked to Alzheimer’s.

Professor David M. Holtzman, who led the study, said:

“We showed that poor sleep is associated with higher levels of two Alzheimer’s-associated proteins.

We think that perhaps chronic poor sleep during middle age may increase the risk of Alzheimer’s later in life.”

Alzheimer’s disease is characterised by gradual cognitive decline and memory loss.

Previous research has shown a link between poor sleep and cognitive problems.

For example, people with sleep apnea — when breathing stops repeatedly during the night — are at risk of developing mild cognitive impairment ten years earlier.

For the study, the effects of sleep apnea were simulated.

People’s deep sleep was disrupted in such a way that they did not wake during the night, but they also did not feel refreshed in the morning.

Levels of the two proteins — called amyloid beta and tau — were both measured by spinal taps.

Dr Yo-El Ju, the study’s first author, explained the results:

“We were not surprised to find that tau levels didn’t budge after just one night of disrupted sleep while amyloid levels did, because amyloid levels normally change more quickly than tau levels.

But we could see, when the participants had several bad nights in a row at home, that their tau levels had risen.”

The scientists do not think that one night or a week of poor sleep is enough to cause Alzheimer’s.

The protein levels probably return to normal with better sleep.

Dr Ju said:

“The main concern is people who have chronic sleep problems.

I think that may lead to chronically elevated amyloid levels, which animal studies have shown lead to increased risk of amyloid plaques and Alzheimer’s.”

It is vital that we get enough slow-wave or deep sleep, as this is when the brain is cleared of waste products.

Dr Ju said:

“Many, many Americans are chronically sleep-deprived, and it negatively affects their health in many ways.

At this point, we can’t say whether improving sleep will reduce your risk of developing Alzheimer’s.

All we can really say is that bad sleep increases levels of some proteins that are associated with Alzheimer’s disease.

But a good night’s sleep is something you want to be striving for anyway.”

The study was published in the journal Brain (Ju et al., 2017).

Get FREE email updates to PsyBlog

Hello, and welcome to PsyBlog. Thanks for dropping by.

This site is all about scientific research into how the mind works.

It’s mostly written by psychologist and author, Dr Jeremy Dean.

I try to dig up fascinating studies that tell us something about what it means to be human.

Get FREE email updates to PsyBlog. Join the mailing list.

Author: Jeremy Dean

Psychologist, Jeremy Dean, PhD is the founder and author of PsyBlog. He holds a doctorate in psychology from University College London and two other advanced degrees in psychology. He has been writing about scientific research on PsyBlog since 2004. He is also the author of the book "Making Habits, Breaking Habits" (Da Capo, 2013) and several ebooks.