Taking longer to reach the rapid eye movement (REM) stage of sleep could mean you are more likely to develop dementia.
Your dreams could predict your likelihood of developing dementia, according to a new study. Research has found that taking longer to reach the rapid eye movement (REM) stage of sleep is linked to Alzheimer’s disease.
Alzheimer’s disease is the most common form of dementia, a progressive condition that affects almost one million people in the UK. It is most common in people over the age of 65 with initial symptoms often involving memory loss.
However, the study, which was published in Alzheimer’s & Dementia journal, has suggested this sign at night might work as one way to identify the condition early on. Or it may be a risk factor for dementia, scientists said.
As part of the research, the team analysed data on 128 participants. A total of 64 of them had Alzheimer’s disease, 41 had mild cognitive impairment, and the rest had normal, healthy cognition.
Participants with other neurodegenerative disorders like Parkinson’s disease were excluded. As were people with sleep-related movement disorders or those who use antipsychotic drugs.
All participants underwent cranial MRIs, bloodwork, and a number of cognitive tests before the start of the study, and their medical histories were studied. They also underwent a number of tests.
This included an overnight sleep study called polysomnography to examine brain waves and other physical functions like eye movement and breathing during sleep. Through this, scientists were able to work out when participants’ REM sleep occurred.
Study participants also underwent PET scans to look at amyloid beta levels, which are known indicators of Alzheimer’s disease alongside other biomarkers.
It was discovered that participants with the longest REM latency (REML) were at greater risk of Alzheimer’s. REML refers to the amount of time it takes for someone to reach REM for the first time after falling asleep.
More specifically, these participants had increased levels of p-tau181 and amyloid beta and lower levels of plasma brain-derived neurotrophic factor compared to participants with the shortest REML. These are all indicators of Alzheimer’s.
On top of this, getting less REM sleep and deep sleep was found to be associated with higher levels of p-tau181, a protein that is associated with certain neurological conditions such as Alzheimer’s. Study author Yue Leng, an associate professor at the University of California, told Medical News Today: “REM sleep, especially the time it takes to enter REM sleep, is potentially important for Alzheimer’s disease (AD).
“The importance of this sleep metric has been largely ignored previously. We don’t know if the correlation is causal, but REM sleep latency can potentially serve as a marker and help with the early detection of AD.”
However she added: “More research is needed to understand the biological underpinnings of REM sleep latency and its implications for AD (if the relationship is causal).”
This is not the first time a link has been made between dementia and REM sleep. A study, published in the journal Neurology in 2017, found that people who went on to develop dementia spent an average of 17 percent of their sleep time in REM sleep compared to 20 percent for people who didn’t go on to develop dementia.
The study also found people who developed dementia tended to have longer intervals between periods of REM sleep, with an average of 87 minutes compared to 70 minutes for people who didn’t develop dementia.
