Poor sleep 'may cause Alzheimer's'
Poor sleep could be a cause of Alzheimer's disease, research has suggested.
A lack of regular deep sleep allows a toxic protein known as beta-amyloid to increase in the brain, attacking the mind's memory faculties.
The study by Berkeley, University of California says a "vicious cycle" emerges where the protein build-up not only corrodes memory, but also disrupts sleep further.
Over time, this can develop into the degenerative brain disease Alzheimer's, a form of dementia characterised by the death of brain cells.
The relationship between sleep and memory loss prompted by beta-amyloid was suspected after heavy build-ups were discovered both in people suffering from Alzheimer's and those with sleeping disorders.
Researchers welcomed the discovery, saying they hoped they could prevent future memory loss through the treatment of sleep deprivation with methods including exercise and behavioural therapy.
A lack of non-REM sleep was identified as playing an important role in the process, as it is a form of deep sleep which helps the mind transfer short-term memories into an area of the brain used for longer-term retention.
Professor Matthew Walker told Nature Neuroscience, which published the study: "This discovery offers hope. 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."
The latest study tested the memory of 26 adults functioning on varying levels of sleep, finding a "very suggestive" link between memory loss and sleep deprivation.
Participants memorised 120 word pairs before scans were used to monitor their brain activity as they slept. They were then tested again in the morning.
Neuroscientist William Jagust, also involved in the study, said: "Over the past few years, the links between sleep, beta-amyloid, memory, and Alzheimer's disease have been growing stronger.
"Our study shows that this beta-amyloid deposition may lead to a vicious cycle in which sleep is further disturbed and memory impaired."
Fellow expert Bryce Mander added: "The data we've collected are very suggestive that there's a causal link. If we intervene to improve sleep, perhaps we can break that causal chain."
Dr Eric Karran, director of research at Alzheimer's Research UK, said: " This small study suggests that 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 retrieval.
"It is always 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. With 225,000 people a year in the UK developing dementia, it is critical that we invest in research to find ways to tackle the condition head-on."