The Sleep Mistake That Could Raise Alzheimer’s Risk
With Alzheimer’s disease on the rise and limited treatment options available, understanding how to lower the risk has become increasingly important. A recent study published in the Journal of Clinical Sleep Medicine examines how specific patterns of sleep—known as sleep architecture—may relate to changes in the brain that are commonly associated with Alzheimer’s.
Sleep architecture refers to the various stages the brain cycles through during rest. These include:
- Stage 1: The initial phase of light sleep, lasting only 1 to 5 minutes, during which muscles begin to relax.
- Stage 2: A deeper stage that typically lasts around 25 minutes, characterized by further relaxation of the body.
- Stage 3: The deepest and most restorative phase, known as slow-wave sleep, marked by consistent heart rate, breathing, and brain activity.
- Stage 4 (REM sleep): Rapid eye movement sleep involves increased brain activity, irregular heart rate and breathing, and is crucial for dreaming and memory consolidation.
Most people move through these stages multiple times each night. Past research has linked poor sleep quality and excessive sleep duration to an increased likelihood of developing dementia. However, the direct impact of specific sleep phases on brain regions particularly vulnerable to Alzheimer’s hadn’t been thoroughly explored—until now.
Alzheimer’s is marked by the gradual shrinking of the brain. Certain areas, including the hippocampus, parahippocampal area, entorhinal cortex, inferior parietal lobule, precuneus, and cuneus, are particularly susceptible to this deterioration. Additionally, small brain bleeds—known as cerebral microbleeds—have been connected to the disease and are considered indicators of small vessel damage in the brain.
To better understand the link between sleep and these brain changes, researchers studied 270 participants from the Atherosclerosis Risk in Communities (ARIC) Study. Participants underwent overnight sleep studies to record their sleep phases. More than a decade later, researchers conducted brain imaging to assess structural changes and the presence of microbleeds.
They discovered that individuals who spent less time in slow-wave sleep tended to have reduced volume in the inferior parietal lobule and cuneus. Similarly, lower amounts of REM sleep were associated with smaller inferior parietal and precuneus regions. When adjusting for other factors, the strongest connection was between reduced REM and slow-wave sleep and shrinkage in the inferior parietal lobule.
Interestingly, the frequency of night-time awakenings and the presence of microbleeds didn’t show any significant association with the size of these Alzheimer’s-prone regions.
According to the study’s authors, this is the first research of its kind to draw a direct connection between sleep patterns and atrophy in areas of the brain most affected by Alzheimer’s in older adults.
The findings suggest that a lack of restorative sleep may contribute to brain volume loss in key regions. Previous studies have shown that sleep plays a role in removing toxins from the brain, which could help explain these results.
Medical News Today consulted with sleep expert Dr. Chelsie Rohrscheib, who emphasized that slow-wave and REM sleep are essential for brain maintenance, cognitive function, and removing waste from brain cells. She pointed out that Alzheimer’s disease involves the buildup of harmful proteins in the brain, which are typically cleared during slow-wave sleep by a system known as the glymphatic system. Without sufficient deep sleep, this cleanup process may be impaired.
Psychologist Dr. Leah Kaylor elaborated further, explaining that during sleep, the brain contracts slightly, allowing cerebrospinal fluid to flow more freely. This fluid acts like a “car wash,” helping flush out waste products, including beta-amyloid and tau—proteins associated with neurodegeneration.
The study underscores the importance of deep, uninterrupted sleep in maintaining brain health and possibly lowering the risk of Alzheimer’s disease.
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