Sleep apnea is more about snoring that keeps people awake or makes one fall asleep when driving. It may also impair memory.
Obstructive sleep apnea is a condition where breathing repeatedly stops or becomes shallow during sleep because the airway gets blocked or partially blocked.
These interruptions lower oxygen levels through the night and fragment sleep.
Over time, that kind of stress on the body — and brain — can cause problems beyond just daytime sleepiness.
Untreated Sleep Apnea May Mean Memory Impairment
A study published online in Neurology explores how this condition might be connected to changes in the brain areas involved in memory.
The repeated drops in oxygen during sleep will affect the brain. All those episodes of paused breathing mean less oxygen to the brain throughout the night.
Though blood circulation itself in the brain isn’t interrupted, the blood in the brain during sleep becomes low in oxygen when you have untreated sleep apnea.
The study says that this might lead to problems with memory, though the study also nots that proof of cause and effect has not been established.
Untreated Sleep Apnea = Low Oxygen
In obstructive sleep apnea, throat muscles relax during sleep and temporarily block airflow.
This forces the brain to repeatedly wake the body just enough to restart breathing, but not enough to full consciousness. This is why a person can have hundreds of sleep-disordered breathing events overnight yet not be aware of all these stops and restarts.
Each interruption can reduce blood oxygen levels. Over time, that pattern may strain small blood vessels in the brain.
REM sleep — the stage most associated with vivid dreaming and memory processing — appears to be especially important in this process.
REM: Rapid Eye Movement
REM sleep is thought to play a role in memory consolidation and emotional processing.
Because of that, researchers wanted to see whether oxygen drops during this stage were linked to changes in brain structure.
The paper explains that low oxygen levels during sleep — especially during REM — may contribute to cognitive decline by damaging small blood vessels in the brain.
That damage could then affect regions involved in memory.
How the Study Was Done
The study included 37 older adults with an average age of about 73. None had diagnosed cognitive impairment, and none were using sleep medications.
Of these participants, 24 were diagnosed with obstructive sleep apnea.
All participants underwent overnight sleep studies that tracked oxygen levels across different sleep stages, including REM sleep.
They also received brain scans to look at structural changes in memory-related regions.
Researchers found that lower oxygen levels during REM sleep were associated with more “white matter hyperintensities” — bright spots seen on brain scans.
These spots are believed to reflect damage in brain white matter, often linked to injury in small blood vessels.
The data also showed that the more time participants spent with oxygen levels at or below 90%, the more white matter damage they tended to have.
Levels at or below 90% are generally considered medically concerning.
The study went further by looking at specific areas involved in memory, including the hippocampus and the entorhinal cortex.
Participants with more white matter damage tended to have reduced hippocampal volume and thinner entorhinal cortex tissue — both changes associated with memory decline.
On top of that, performance on memory tests that measured sleep-related memory processing was linked to reduced thickness in the entorhinal cortex.
In simpler terms, worse oxygen levels during sleep were associated with structural brain differences and weaker memory performance in this group.
What may have been happening?
Repeated oxygen drops during sleep may damage small blood vessels in the brain.
That vascular damage may then affect brain regions responsible for storing and processing memory.
Over time, this could help explain why obstructive sleep apnea has been linked to cognitive decline and conditions like Alzheimer’s disease.
But again, the researchers are careful to point out that this study does not prove sleep apnea directly causes brain degeneration — it only shows an association.
More research with larger and more diverse groups is needed to confirm the findings.
