Poor sleep 'boosts proteins linked to Alzheimer's'

11th July 2017 – We all know how a good night's sleep can refresh the mind. Now, a small study has demonstrated how poor sleep might do the opposite.

The findings, in the journal Brain, suggest that interruptions to deep sleep can cause a build-up of proteins in the brain associated with Alzheimer's disease.

Plaque and brain tangles

The researchers found that just one night's poor sleep causes an increase in amyloid beta, a protein that forms plaques in the brain. Also, a week of interrupted sleep sees an increase in another brain protein, tau, which causes damaging tangles in brain cells.

Around 530,000 people have Alzheimer's disease in the UK. It leads to gradual memory loss and a deterioration in thinking ability.

A growing body of research suggests a link between the disease and poor sleep. However, scientists are still trying to unravel the mechanism behind any connection.

Deep, slow-wave sleep

This latest study is the first to suggest a connection between interruptions to deep, dreamless, slow-wave sleep and the build-up of more amyloid proteins, according to Dr Yo-El Ju, an assistant professor of neurology at Washington University School of Medicine in the US, which led the investigation.

"Certainly, it seems like people who have poor sleep or sleep disorders are at higher risk of Alzheimer’s disease," says Dr Ju. "But also, the brain changes of Alzheimer's disease seem to worsen sleep."

Dr Ju and her colleagues recruited 17 healthy adults aged 35 to 65 who had healthy brains and no sleep problems.

Sounds that go beep in the night

The researchers wrote a computer program designed to play a rising crescendo of beeps through headphones to disrupt deep, slow-wave sleep in half of the participants.

"Our goal was not to wake them up," says Dr Ju. "We wanted them to continue to sleep, just in lighter stages of sleep."

The remaining participants were allowed to sleep undisturbed.

The following morning, the people who had endured disrupted sleep reported feeling tired and unrefreshed, despite having had as much sleep as usual.

After a month or so the volunteers switched, so that those who slept uninterrupted had their sleep disturbed in a repeat of the experiment.