Australian scientists have found that a reduction in REM sleep, during which a person observes dreams, is associated with a high risk of developing dementia. A related study is published in the journal Neurology and is briefly reported by the American Academy of Neurology.
The experiment involved 321 people from Massachusetts (USA) with an average age of 67 years. They were monitored (including monitoring the rhythms of the brain) for about 12 years. During this time, 32 people were diagnosed with one of the forms of dementia, 24 - Alzheimer's disease.
It was the reduction in REM sleep, and not other periods, as the authors showed, that was associated with dementia. In fact, a one percent decrease in REM sleep was positively associated with a nine percent increase in the risk of developing dementia.
“Our results point to REM sleep as a predictor of dementia,” said co-author Matthew Pase. “Going forward, we have to understand the reasons why a short duration of REM sleep is associated with a greater risk of dementia.”
There are five sleep phases in total. REM sleep is the last of these and is characterized by increased brain activity. At this time, a person usually observes dreams, and his eyeballs make rapid movements.