- Less REM sleep in older adults increases the risk of developing dementia
- There is a nine-fold increase in developing dementia risk in every one percent reduction in REM sleep
Rapid eye movement (REM) sleep is a unique sleep stage when dreams occur. Individuals who get less REM sleep might be at greater risk of developing dementia, reveals a new study.
The new study was in the online issue of Neurology®,
the medical journal of the American Academy of Neurology.
‘For every one percent reduction in REM sleep, there is a nine-fold increase in the risk of developing dementia in the elderly.’
What happens During different stages of REM Sleep?
There are five stages of sleep, which are as follows:
- Stage one is light sleep
- In stages two, three and four the body begins to prepare for deeper sleep and
- Stage five is REM sleep
During this dream stage, the eyes move rapidly, and there is increased brain activity. The body temperature increases, pulse quickens and breathing is faster.
In the first stage, sleep occurs for about one hour to an hour-and-a-half and then recurs multiple times throughout the night.
Matthew P. Pase, Ph.D., of the Swinburne University of Technology in Australia said that sleep disturbances are commonly seen in people with dementia. However, very little is known about the various stages that occur during sleep and their role in dementia risk.
Pase said, "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."
For this study, the research team observed 321 people, who's average age is 67 and who are from Massachusetts participated in The Framingham Heart Study.
During the study, sleep cycles of every participant were measured. The research team collected the sleep data and then followed these participants for an average of 12 years.
During this period, nearly 32 people were found to be diagnosed with some form of dementia, and of which, about 24 of them were determined to have Alzheimer's disease.
Participants who developed dementia during this time spent an average of 17 percent of their sleep time in REM sleep when compared with 20 percent of those who did not develop dementia.
The research team adjusted the participants based on their age and sex and found an association with a lower percentage of REM sleep and a longer time to get to the REM sleep stage and an increased risk of dementia.
For every percent reduction in REM sleep, it was found that there was a nine percent increase in the risk of dementia, reveals the research team.
Even after the research team adjusted for various other factors that can increase the risk of dementia or sleep like heart disease factors, depression symptoms and use of medication.
Other stages of REM sleep were found to be not associated with an increased risk of dementia.
Pase said, "Our findings point to REM sleep as a predictor of dementia and 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."
The limitations of this study were that the sample size was small and there is a need to conduct the study on a larger group to confirm these findings. The data of participants who work shifts are not available. Shift working people can have unusual sleep patterns that could lead to sleep disorders.
What is REM Sleep?
REM Behavior Disorder (RBD), a sleep disorder, where a person acts out dramatic or violent dreams during Rapid Eye Movement (REM) sleep.
A sleep cycle is defined by Non-Rapid Eye Movement (NREM) sleep, that comprises of four stages, followed by a period of Rapid Eye Movement (REM) sleep.
A typical sleep cycle lasts for about 100 - 110 minutes long, beginning with NREM sleep and transitioning to REM sleep after 80 - 100 minutes.
REM sleep is also referred to as the 'dream sleep,' because most of the dreams occur during this stage. The temporary muscle paralysis which occurs during this phase is a protective mechanism, to stop us from acting out the dreams.