Spending less time in THESE two sleep stages may contribute to Alzheimer's, says study

Alzheimer's is a progressive brain disorder, that causes memory loss and other cognitive decline. It's the most common cause of dementia in older adults, and can wreak havoc on one's health, and not just mental. It carries a poor prognosis, and has currently no cure, though timely treatment can help manage symptoms, and slow down its progress.


What causes Alzheimer’s?
While the verdict on its cause is not clear, Alzheimer's is thought to be caused by a combination of factors, including abnormal protein buildup (plaques and tangles) in the brain, age-related changes, genetic predispositions, and lifestyle/environmental influences, ultimately leading to brain cell damage and death. Sleep troubles are also said to be linked to the disease, and now, new research says that poor sleep in two stages of the sleep cycle can contribute to Alzheimer’s.

Sleep cycles
To understand this better, let us first try to understand the various sleep cycles on a normal night...

Stage 1: This is the first stage soon after you have dozed off. It is relatively light sleep, as muscles begin to relax. Lasts for just 1–5 minutes.

Stage 2: Slighter deeper sleep, this phase lasts around 25 minutes, as the body relaxes more and more.

Stage 3: This is the deepest stage of sleep, also known as slow-wave sleep. Your heart rate, breathing, and brain waves become more regular.

Stage 4: Known as the rapid-eye movement (REM) sleep due to the movement of the eyes, in this phase breathing becomes faster and blood pressure and heart rate become less regular.


Connection of sleep and Alzheimer’s
A recent study published in the Journal of Clinical Sleep Medicine explores the connection between sleep patterns and brain regions associated with Alzheimer's disease. Conducted over a period of 13 to 17 years, the research examined brain development across all stages of sleep. The scientists employed polysomnography to evaluate sleep architecture and later used MRI scans to assess anatomical brain features, including brain volume and signs of cerebral microbleeds. They also analyzed the proportion of slow-wave sleep, REM sleep, and nighttime arousal frequency.

What did it find?
The study's findings suggest that decreases in slow-wave and REM sleep may significantly contribute to reduced volume in the inferior parietal region of the brain. Previous research has demonstrated that sleep aids in removing toxins from the brain. The authors propose that this process may explain why sleep reductions could lead to neurological atrophy, potentially linking disrupted sleep patterns to increased risk of neurodegenerative conditions.

What does this mean?
The study essentially means that good, quality sleep is imperative to brain development, and one should fix their sleep cycle early on in life to avoid issues later on.