Rapid eye movement (REM) is a specific sleep stage characterised by high-level brain activity and vivid dreams. Typically, human beings complete a series of REM sleep periods during every sleep session. According to a study which was published in the Journal of Neurology in 2017, researchers discovered that dementia patients had a history of less REM sleep. Conversely, healthy people who did not have any cognitive issues had a history of sufficient REM sleep.
Yes, this study did not prove that dementia results from low REM sleep levels, but it did demonstrate that there is a link between the two. For instance, it is possible the high-level brain activity which occurs during REM sleep can prevent age-related damage to specific neural pathways, which connect the nervous systems. Additionally, it is also possible that reduced REM sleep may result from stress, anxiety, or any other factor known to increase vulnerability to dementia.
Nevertheless, more studies are needed to help understand the complex relationship which exists between dementia and sleep, as well as help to explain why dementia patients tend to have had decreased REM sleep. Once the researchers get to the bottom of this dilemma, new avenues to diagnose, prevent, and manage dementia could be discovered.