Reduced REM and Deep Sleep Linked to Alzheimer's-Related Brain Changes: Study

Yale-led research finds sleep quality may be a modifiable risk factor for Alzheimer's​

New Delhi, April 1 — A new study has found that spending less time in key stages of sleep—particularly REM and deep (slow wave) sleep—may be linked to brain changes associated with Alzheimer's disease, a progressive neurological disorder that affects memory, cognition, and speech.

Published in the Journal of Clinical Sleep Medicine, the research highlights how insufficient time in restorative sleep phases corresponds with reduced volumes in specific brain regions known to degenerate in Alzheimer's patients.

Sleep architecture and brain health​

The study focused on four distinct stages of sleep that occur throughout the night, each responsible for different physiological functions. The REM (Rapid Eye Movement) stage, known for vivid dreaming and heightened brain activity, and slow wave sleep, the deepest stage of sleep, are especially crucial for brain repair and memory consolidation.

Researchers from Yale School of Medicine analyzed brain scans of 270 individuals around the age of 60. These scans were compared with MRI scans taken 13–17 years later. They observed that individuals who spent less time in REM and deep sleep exhibited smaller brain volumes in regions typically affected early in Alzheimer's, such as the inferior parietal lobule.

"This is significant because it helps us understand how sleep deficiency, a common issue in middle-aged and older adults, might contribute to Alzheimer’s disease development and cognitive decline," said lead author Gawon Cho, a postdoctoral associate at Yale School of Medicine.

Key findings​

• Lower time spent in REM and slow wave sleep was linked to reduced volume in the inferior parietal region, which is critical for attention, language, and social cognition.
• The study reinforces prior findings that Alzheimer's patients often have a smaller hippocampus, the brain's memory center.
• Sleep-related neuroactivity might influence brain atrophy, potentially raising Alzheimer's risk.

"Our findings provide preliminary evidence that reduced neuroactivity during sleep may contribute to brain atrophy, thereby potentially increasing the risk of Alzheimer's disease," Cho explained.

Sleep as a modifiable risk factor​

The researchers suggest that sleep architecture—the structure and pattern of sleep cycles—could serve as a modifiable risk factor for Alzheimer’s disease and related dementias. This opens up new possibilities for interventions aimed at improving sleep quality to delay or reduce Alzheimer's onset.

"Sleep architecture may be a modifiable risk factor, allowing for interventions to reduce risk or delay Alzheimer's onset," Cho added.

While the study offers important insights, the authors emphasize the need for further research to fully understand how sleep cycle changes can influence the development and progression of Alzheimer’s disease.