How Does Sleep Apnea Impact the Brain?

You’ve probably heard about the physical side effects of sleep apnea, like high blood pressure, heart disease, and diabetes. But obstructive sleep apnea (OSA) can take as big a toll on the brain as it does on the heart. Changes in brain matter and damage to neurons caused by sleep deprivation can lead to memory loss and other complications. Recent studies have shown that sleep apnea also changes the levels of neurotransmitters in the brain. What does this mean? The good news is, this damage may be reversible.

Sleep Apnea and Memory Loss

People with sleep apnea tend to experience a range of daytime mental symptoms primarily due to the lack of restorative sleep from waking up multiple times an hour throught out the entire night. These symptoms include fatigue, shortened attention span, moodiness, and especially reduced short-term recall.  

Research suggests that people with sleep apnea have trouble converting short-term memories into long term ones. Consolidating memories, or storing experiences so that they can be accessed later, is a vital link in the memory-creating process that occurs during sleep. When slumber is impacted by a disorder, people have trouble incorporating and categorizing their experiences, which leads to impaired memory formation and forgetfulness.

Sleep Apnea Changes the Shape of the Brain

The mental symptoms of sleep apnea are more serious than the temporary grogginess caused by drowsiness. During an apnea (Greek for “without breath”) the subject actually stops breathing, which starves the brain of oxygen. This duress, paired with chronic fatigue, can cause physical, measurable brain damage.

Researchers at UCLA compared the mammillary bodies—structures in the brain that are important in memory storage—of several adults suffering from sleep apnea with those of healthy people. They found that the bodies in the troubled sleepers were nearly 20% smaller than in their untroubled counterparts.

Furthermore, multiple studies have discovered a decrease in both gray and white matter in the brains of subjects with OSA. A study published in Sleep journal found significant reductions in gray matter concentrations in certain areas of the brain. This led principal investigator Doctor Seung Bong Hong of the Sungkyunkwan University School of Medicine in Seoul to conclude that “Poor sleep quality and progressive brain damage induced by OSA could be responsible for poor memory, emotional problems, decreased cognitive functioning and increased cardiovascular disturbances.” In 2008, a UCLA study found significant damage in the brain’s fiber pathways and structural alterations in its white matter, especially in areas that regulate mood, memory, and blood pressure.

Sleep Apnea Changes How the Brain Works

A February 2016 study published in the Journal of Sleep Research by the UCLA School of Nursing investigated the injury caused to the insular cortex of the brain by sleep apnea. They studied levels of two important brain chemicals, called neurotransmistters: glutamate and gamma-aminobutyric acid, known as GABA. Unlike previous studies, “we actually found substantial differences in these two chemicals that influence how the brain is working,” said Paul Macey, the lead researcher on the study and an associate professor at the UCLA School of Nursing.

 “It is rare to have this size of difference in biological measures,” Macey said. “We expected an increase in the glutamate, because it is a chemical that causes damage in high doses and we have already seen brain damage from sleep apnea. What we were surprised to see was the drop in GABA. That made us realize that there must be a reorganization of how the brain is working.”

Macey says the study’s results are, in a way, encouraging. “In contrast with damage, if something is working differently, we can potentially fix it.”

“What comes with sleep apnea are these changes in the brain, so in addition to prescribing continuous positive airway pressure, or CPAP — a machine used to help an individual sleep easier, which is the gold standard treatment for sleep disturbance — physicians now know to pay attention to helping their patients who have these other symptoms,” Macey said. “Stress, concentration, memory loss — these are the things people want fixed.”

Can the Damage to the Brain be Restored?

The link between sleep apnea and changes in the state of the brain is important news for clinicians, Macey said. Especially because there is evidence that treating sleep apnea, such as with using PAP therapy, may return patients’ brain chemicals back to normal levels. Researchers plan to continue investigating this.

According to the American Academy of Sleep Medicine, a pair of studies evaluated the effects of CPAP therapy on several subjects who had seen significant damage to their brain matter. They found that after a year of CPAP treatment, the patients’ white matter was almost completely restored, while their gray matter saw substantial improvement after only three months.

This is in line with other studies that have confirmed that CPAP treatment, when used regularly, can almost completely alleviate the symptoms and effects of sleep apnea.

Are you or a loved one suffering with these brain-related symptoms of sleep apnea? If so, talk to your doctor and find out more about testing for sleep apnea. If you’re ready to schedule a sleep study, click below for more information.

Request a sleep study

Editor’s Note: This post was originally published in November 2014 and has been edited and updated for accuracy and comprehensiveness. 


American Academy of Sleep Medicine
Macey, P. M., Sarma, M. K., Nagarajan, R., Aysola, R., Siegel, J. M., Harper, R. M. and Thomas, M. A. (2016),
Obstructive sleep apnea is associated with low GABA and high glutamate in the insular cortex. Journal of
     Sleep Research. doi: 10.1111/jsr.12392 
>Science Daily
University of California – Los Angeles. “Memory Loss Linked To Common Sleep Disorder.” ScienceDaily. ScienceDaily, 13 June 2008.

Photo Credit: Health Magazine

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Comments previously posted on the Sleep Better Blog:

Kelley Carey

4/3/2015, 5:47:31 PM

Good article

Mosley Dave

5/5/2015, 4:24:09 PM

My doctor says I have sleep apnea. I feel terrible. Ringing ears, no memory, loss of confidence and more. I hope this is the answer. Feel free to comment.

5/11/2015, 11:10:11 AM

Hi, thanks for commenting! Ringing ears, loss of memory, and loss of confidence are all associated with classic sleep apnea. In particular, memory and confidence are connected to REM sleep, serotonin, and oxygen intake, which are disturbed during sleep apnea. We recommend having a sleep study to test for the disorder. If a diagnosis of OSA is confirmed, you will likely see improvements in all three areas. Here is a link to look into sleep studies: Feel free to contact us for more information!

Chan Kim

12/27/2015, 4:48:33 AM

Wow, I’m relieved my possible brain damage can be reversed by CPAP! It’s my 4th day of using CPAP and I was worried my brain might have already been damaged to some degree.

1/4/2016, 3:19:21 PM

Keep it up! CPAP isn’t easy, but it’s effective.

Jacqueline Milford

8/3/2016, 6:12:16 PM

I have been using CPAP for a while now, but my memory and cognitive function are not really improving. I have noticed a lot of other improvements, but I still cannot remember anything, have a hard time focusing, and cannot seem to function well cognitively. I cannot even tell you how long I have been using my machine. I hope that I get better, and that somehow the damage is reversed. I went 8 or 9 mos (just a guess) with my apnea at its worst. I would wake up and thirty minutes later go into the bathroom and my lips would still be blue. Please, if there is ever any doubt, go get yourself tested immediately.

8/4/2016, 3:10:58 PM

Hi Jacqueline. Thanks for sharing your struggle. I’m glad you’re seeing a lot of other improvements since starting CPAP.


  1. Sonia Reply

    I don’t know how reversible the damage is. Hypoxic brain damage may be partially reversible but, I believe, some is very permanent.

    Whether drowning, suffocating, choking, asthma attack or sleep apnea causes the brain injury – the reversibility all depends on how long the brain was starved of oxygen.

    My OSA was only discovered because they were trying to find out what was causing my secondary polycythemia.

    On the night of the sleep study my blood oxygen dropped to below 50%. I’m sure it has been lower, with hind sight, because cpap therapy cured my drenching night sweats incidently.

    I didn’t even sweat on the night the study was done but stopped breathing for a minute and a half!!

    Now I feel like a person in the early stages of dementia – I forget things, not able to stay mentally focussed, and believe my IQ has suffered permanently.

    Cpap has stopped the progression of my cognitive difficalties but it has not reversed it at all.

    There needs to be more weight given to the seriousness of permanent brain damage .. and less bullshit that therapy can undo the death of areas of the brain starved of oxygen.

    If cpap could perform this miracle then why doesnt it work for drowning or stroke victims etc. who have PERMANENT hypoxic brain damage?

    I’m greatful for cpap therapy because it had stopped more damage accumulating and keeps me alive – but this notion of it bringing dead areas of the brain back to life is too good to be true and probably isn’t.

    • Julia Rodriguez Reply

      Hi Sonia. The cognitive effects from sleep apnea is a serious issue and one that warrants more attention and research. The 2016 UCLA study proposed that some of the “damage” done to the brain by sleep apnea is actually a change in levels of chemicals that can be completely restored with CPAP therapy, rather than a reversal of “permanent” damage. So glad to hear that therapy is helping you.

  2. Darla Colthurst Reply

    Sleep apnea has been linked to many health problems and consequences, including high blood pressure, fatigue, and – as it was recently found – brain damage.

    • Julia Rodriguez Reply

      Hi Darla. Yes, the consequences of untreated sleep apnea should not be ignored.

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