Poor sleep – particularly a lack of deep, restorative slumber – could be linked to the build-up in the brain of the toxin proteins thought to trigger Alzheimer’s.
It is believed poor sleep quality is a channel through which the beta-amyloid protein can attack the brain’s long-term memory.
“Our findings reveal a new pathway through which Alzheimer’s disease may cause memory decline later in life,” said Matthew Walker, professor of neuroscience at the University of California, Berkeley.
The US researchers tested the memories of a group of adults aged between 65 and 81 to see how they functioned on varying levels of sleep.
Those deprived of regular deep sleep had the highest levels of beta-amyloid, it was found, and performed worst in memory tests, with some forgetting more than half of 120 word pairs they had been given the previous day.
The study also revealed a “vicious cycle” in which the protein not only corrodes memory, but also disrupts sleep further.
The University of California team welcomed the discovery, saying they hoped they could prevent future memory loss by treating sleep deprivation with exercise and behavioural therapy.
Professor Walker added: “Sleep could be a novel therapeutic target for fighting back against memory impairment in older adults and even those with dementia.
“Sleep is helping wash away toxic proteins at night, preventing them from building up and from potentially destroying brain cells. It’s providing a power cleanse for the brain.”
Doctor Eric Karran, director of research at Alzheimer’s Research UK, said: “A bad night’s sleep can play havoc with memory and thinking skills in all of us in the short term.
“This small study suggests the build-up of abnormal proteins in the brain as we age is associated with problems in sleep cycles, which could lead to difficulties with memory.
“It is difficult to tease apart cause and consequence and as this study was carried out in healthy older people, rather than in those with dementia, it is not possible to conclude that disrupted sleep causes memory difficulties in the condition.
“This study is a snapshot and so it would be interesting to expand the research to look at changes in memory over time.”