By SUSAN CALLAHAN, Featured Columnist
Both dementia and Alzheimer's disease, a type of dementia, have long been linked to sleep and dream disturbances.
With dementia, the entire structure of your sleep is altered. Called the "architecture of sleep", the structure of sleep occurs in five distinct phases, The first four phases of sleep are non-REM and the last, final stage of sleep is REM. REM stands for "rapid eye movement". Literally, if you took a video of yourself sleeping during the REM phase, you would see that your eyes are flicking back and forth quickly while your eyelids are closed.
The first four phases of sleep take about 90 minutes. After the first 90 minutes, the remaining hours of sleep are REM sleep, your deepest sleep.
Why Dreaming Is Important to Your Brain's Health
"To sleep, perchance to dream - ay , there's the rub, for in this sleep of death what dreams may come.", Shakespeare's Hamlet wondered.
We humans pride ourselves on being rational and logical. But we all take a nightly flight into with unreality and wake up feeing better for it. We have long attributed meaning to dreams, believing that they tell us something hidden from ourselves perhaps about our lives or our inner selves.
Are our dreams merely entertaining escapes into fantasy or do they serve another purpose? Scientists are beginning to believe that latter, that we actually need dreams to stay healthy.
It is during REM sleep that you dream. Deprived of REM sleep by torture, prisoners become psychotic.
Dreams are believed to help us consolidate memory. To keep your sanity intact, you must sleep. And to keep your memory intact, you must dream.
Another feature of REM sleep is that your brain inhibits muscle movements, which is why most of us do not sleepwalk or act out movements in our sleep.
People Who Have Less REM Sleep Have Higher Risk for Dementia
In August of 2017, Dr. Matthew Pase and a team of researchers from Swinburne University of Technology set out to discover whether the absence of REM or non-rem sleep raises the risk of developing dementia.
The researchers drew 321 people from a larger study conducted in the United States (the Framingham Health Study). All of the participants were over 60 years old, with an average age of 67.
Each of the participants were given with devices that measure REM and non-REM sleep (home-based polysomnography). Polysomnography devices measure breathing, the amount of oxygen in your blood, brain waves, body position, heart rate and eye movement.
After 12 years of follow-up, the researchers tallied how many of the people developed dementia and matched that against the evidence of how much REM sleep they got each night.
A total of 32 people developed dementia at the end of 12 years. Of these 32 cases of dementia, 24 were Alzheimer's disease.
Sorting out the percentages of REM and non-REM sleep each person got, the scientists made a startling discovery.
For every 1% less REM sleep you get, your risk for developing dementia rises by 9%.
This extremely strong relation relationship between REM sleep and dementia holds true, even after discounting for other variables such as heart disease/vascular risk, symptoms of depression and medications.
Non-REM sleep, on the other hand, bears no relation to your risk for dementia.
Although the correlation between lack of REM sleep and dementia is strong, we should not take the study's conclusions as gospel. For one thing, the study sample size of 321 people is small. We will need to see the results replicated with a much larger sample size to be more confident of the findings.
Alzheimer's Makes You Dream More Vividly?
Some studies have found that those in the early stages of Alzheimer's experience vivid dreams in which they act out sometimes in a physically violent manner or even falling out of bed. This was the conclusion of a 2007 study from the University of Toronto. The study warns that people with Alzheimer's often have these type of dreams many years before symptoms of Alzheimer's or dementia actually appear.
On the other hand, some sources have warned that those who dream vividly actually are less likely to develop Alzheimer's disease, citing, we believe somewhat in error, the Australian work of Dr. Pase.
Dr. Pase's work did not show that those who dream vividly have lower risk of Alzheimer's. That's going a step or two too far. It found that deep sleep, REM sleep, seems protective against Alzheimer's. Yes, most people dream during REM sleep but those dreams may or may not be vivid. They certainly are not necessarily "vivid" in the sense that the word is understood to mean physically violent.
To be clear, having physically violent dreams does not lower your risk for Alzheimer's or other forme of dementia. The best evidence show that it correlates with an increased risk of dementia.