Disrupted breathing during REM sleep may do more than just interrupt rest—it could be quietly altering brain regions responsible for memory, according to a groundbreaking new study.
Key Points at a Glance
- REM-related sleep apnea is linked to reduced thickness in memory-related brain areas.
- Participants with more REM apnea events had thinner entorhinal and hippocampal cortexes.
- These brain changes may mirror early markers of Alzheimer’s disease.
- The study suggests a specific neurological risk from apnea during REM sleep.
Sleep is supposed to be restorative—but what if certain sleep patterns are silently damaging the brain? According to new research presented by the American Academy of Neurology, obstructive sleep apnea that occurs specifically during the REM (rapid eye movement) phase of sleep may be associated with structural changes in parts of the brain essential for memory. The findings offer an unsettling look into how nighttime breathing disruptions could contribute to cognitive decline.
The study followed 81 individuals with obstructive sleep apnea, using high-resolution brain scans and sleep studies to assess both neural structure and sleep activity. While sleep apnea is commonly known to cause fragmented sleep and daytime fatigue, this study zeroed in on apnea events during REM sleep—when dreaming occurs and the brain processes emotional and procedural memories.
What the researchers discovered is both surprising and concerning: those with higher numbers of REM-related apnea events had notably thinner entorhinal and hippocampal cortexes—two brain regions known for their critical roles in memory formation and spatial navigation. These areas are also among the first to degenerate in the early stages of Alzheimer’s disease.
Even after adjusting for variables such as age, sex, and overall apnea severity, the relationship held. It appears that the disruption caused by repeated oxygen deprivation during REM sleep may trigger or accelerate the thinning of these vital brain structures.
Why is this significant? Traditionally, obstructive sleep apnea has been treated and evaluated largely in terms of overall apnea burden, often without distinguishing between REM and non-REM events. This study suggests that focusing on apnea that occurs during REM could uncover a previously underestimated neurological risk. For many patients, this might mean that standard diagnosis and treatment protocols fail to catch a stealthier but equally dangerous form of the disorder.
The study’s lead author, Diego Z. Carvalho, MD, MS, of the Mayo Clinic, emphasizes that while these findings don’t establish a direct cause-and-effect relationship, they point to a potentially modifiable risk factor for cognitive decline. If confirmed by further research, REM-specific apnea might be an actionable target in the fight against memory-related diseases such as Alzheimer’s.
This research also raises questions about current treatment practices. Many patients use CPAP (continuous positive airway pressure) machines to manage their sleep apnea. But if REM-related events are especially harmful and often occur later in the night—when patients may have already removed their masks due to discomfort—then treatment may be falling short precisely when it is needed most.
The findings underscore the importance of sleep health not just for energy and mood, but for long-term brain integrity. As scientists continue to unravel the complex relationship between sleep and neurological function, it’s becoming increasingly clear that how—and when—we breathe during the night may shape how we remember, think, and age.
Source: American Academy of Neurology
