Current study: sleep disorders increase the risk of dementia

What role does healthy sleep play in the likelihood of developing dementia?
Can our sleep influence the risk of people being more likely to develop dementia? Researchers have now found that the time spent in REM sleep at night affects how high the risk of developing dementia is.

In their current study, scientists from Swinburne University of Technology and Boston University found that a shortened REM sleep phase leads to an increased risk of developing dementia. The doctors published the results of their study in the journal "Neurology".

Effects of a too short REM sleep phase
The experts have found that dementia can be predicted in older people by measuring REM sleep. If people have a shorter REM sleep, the risk of dementia increases significantly. The new study found that a reduction in REM sleep time of just one percent means that sufferers are nine times more likely to develop dementia. In other words, REM sleep is a predictor of dementia, the researchers explain.

What is the REM sleep phase?
During the REM phase of sleep, the eyes move faster and there is increased brain activity. In addition, the pulse beats faster and breathing accelerates. The so-called REM phase usually occurs one to one and a half hours after falling asleep. During the night, the cycles of sleep repeat, so does the REM phase.

Doctors examined older subjects
For their study, the researchers examined a total of 321 people with an average age of 67 years. These subjects had participated in the Framingham Heart Study in the United States. During the examination, the doctors measured the sleep cycles of the participants. The subjects were then medically monitored for an average of twelve years.

32 subjects develop dementia during the examination
During the follow-up period, 32 people were diagnosed with some form of dementia. 24 of these participants were diagnosed with Alzheimer's disease. Subjects who developed dementia spent an average of 17 percent of their sleep time in REM sleep, compared to 20 percent of people who did not develop dementia, the scientists explain.

Other phases of sleep are not associated with the development of dementia
After adjusting the results for age and gender, the researchers found that a lower percentage of REM sleep and a longer time to reach the REM sleep stage are associated with an increased risk of dementia. Even after considering other factors that affect dementia risk or sleep, such as factors for heart disease, symptoms of depression, or the use of medication, the results were still similar, the doctors explain. It was also found that the other stages of sleep were not associated with an increased risk of dementia.

What sleep phases are there?
REM sleep is the fifth stage of sleep and this phase occurs before dreaming. Sleep is divided into the following phases:
- Phase one: light sleep
- Phase Two: The body begins to prepare for deep sleep
- Phase three: deep sleep
- Phase four: deep sleep
- Phase five: REM sleep

Many people with dementia suffer from sleep disorders
Sleep disorders are common in people with dementia. So far, however, little was known about the different stages of sleep and their role in the development of dementia, the experts add. The scientists therefore decided to find out which stages of sleep could be linked to the development of dementia. They found no connection between dementia and deep sleep, but a connection between REM sleep and the risk of dementia was found.

More research is needed
The next step is to determine which mechanisms of REM sleep lead to the greater risk of developing dementia, the researchers explain. By understanding what role sleep plays in the development of dementia, new opportunities could be identified that could significantly improve dementia treatment in the future and delay or even prevent dementia, the scientists hope. (as)

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