Researchers found a link between low levels of rapid eye movement (REM) sleep and dementia risks. Participants who got less REM sleep had higher risks of developing dementia.

Sleep And Dementia

Poor sleep has been previously linked to increased Alzheimer's and dementia risks in various studies. However, there has also been mixed results when it comes to the exact sleep stage correlated to dementia risk.

Now a new study published in the journal Neurology sheds light into REM as a possible link. By using participants of the 1995 to 1998 Framingham Heart Study, researchers conducted overnight assessments of their sleep patterns using a home-based polysomnography.

The 321 participants were all over 60 years of age, with a median age of 67 at the time of the sleep assessment. Researchers followed the participants for 12 years, during the time frame of which 32 people or approximately 10 percent of the participants were diagnosed with a form of dementia, 24 of whom were diagnosed with Alzheimer's disease.

9 Percent Risk Increase For Every 1 Percent REM Decrease

Interestingly, researchers found that those who were diagnosed with dementia spent only 17 percent of their sleep in the REM stage, compared to those who did not develop dementia who spent 20 percent of sleep on REM.

Further, researchers found that every 1 percent decrease in REM sleep resulted in a 9 percent increase in dementia risk, a result that held up even after accounting for other possible risk factors such as depression and medications.

That's not saying that a lack of REM sleep causes dementia. Instead, it shows a strong correlation between the two. Though researchers believe that further studies are needed to fully understand the relationship between the two, they also explain that there are two possible reasons for the correlation.

For one thing, because REM sleep tends to protect the brain's connections that are vulnerable to aging, a lack of it could also mean a lack of protection. On the other hand, it's also possible that it is other dementia risk factors such as anxiety, which causes the lack of REM sleep.

Either way, the current study goes to show just how important sleep is, not just for daily alertness and productivity but also for brain health in the long run.

What Is REM Sleep?

To understand REM, it is important to understand that the brain normally goes through stages during sleep. REM is the fifth stage of sleep, and it is where the brain and body are energized. It comprises 25 percent of the sleep cycle and happens about 70 minutes into sleep.

During REM, signals are sent to the spinal cord to temporarily shut off movement in the arms and legs. It is also the stage of sleep that is often associated with dreaming.

A lack of REM sleep has previously been linked to migraines and the inability to remember that which has been taught before going to bed.

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