Less REM sleep linked with dementia

People who get less rapid eye movement (REM) sleep have a greater risk of developing dementia, according to new research published in the journal of the American Academy of Neurology.

During the study, researchers examined 321 people with an average age of 67. Sleep cycles were measured for each participant over the course of twelve years. During that time, 32 people were diagnosed with some form of dementia and of those, 24 were found to have Alzheimer’s disease.

The people who developed dementia spent an average of 17 per cent of their sleep time in REM, compared to 20 per cent for those who did not develop dementia. After adjusting for age and sex, researchers found links between both a lower percentage of REM sleep and a longer time to get to the REM sleep stage and a greater risk of dementia.

For every per cent reduction in REM sleep there was a 9 per cent increase in the risk of dementia. The results were similar after researchers adjusted for other factors that could affect dementia risk or sleep, such as heart disease, depression symptoms and medication use.

The study’s lead author, Matthew Pase, said: ‘Sleep disturbances are common in dementia but little is known about the various stages of sleep and whether they play a role in dementia risk. We set out to discover which stages of sleep may be linked to dementia and while we did not find a link with deep sleep, we did with REM sleep.’

‘Our findings point to REM sleep as a predictor of dementia. The next step will be to determine why lower REM sleep predicts a greater risk of dementia. By clarifying the role of sleep in the onset of dementia, the hope is to eventually identify possible ways to intervene so that dementia can be delayed or even prevented.’