Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
Sleep Apnea & Poor Memory | Science Behind Memories | Diagnosis
Overview
Sleep apnea is a sleep disorder known to cause disturbed sleep; however, the complications related to sleep apnea are not limited to poor sleep quality. It may also affect overall health, and longevity, and impair cognitive functions, specifically memory.
Continue reading to learn about sleep apnea and how it affects the brain and triggers a decline in memory.
What is Sleep Apnea?
Sleep apnea is characterized by frequent awakening due to interruptions in breathing. It occurs when breathing stops and starts recurrently while a person is sleeping.[1]
Obstructive sleep apnea (OSA) is a common sleep disorder that occurs when throat muscles relax, causing the tongue to fall backward, blocking air passages.
Central sleep apnea occurs (CSA) when the brain fails to send proper impulses to the muscles involved in breathing.[2]
Both these forms of sleep apnea may co-exist in some patients. Sleep apnea impairs the quality of sleep, causing memory problems.
Sleep Apnea & Poor Memory
People often underestimate the power of sound sleep. During sleep, the body works hard to repair and heal damaged tissues to restore optimum health.
A large part of these healing processes involves eliminating built-up toxins in the brain through lymphatic channels.[3]
During the REM stage of deep sleep, our brain cleanses away toxins, allowing it to process and sort out the information gathered during the day. The REM sleep phase is when the memories are consolidated to be recalled for future use.[4]
The lack of REM sleep caused due to sleep apnea can directly impact the brain’s memory processing and consolidation functions.
Let’s find out more about how the brain’s cognitive functions, like memory consolidation, are affected in patients with sleep apnea.
The Science Behind Memory Problems?
Loss of sleep
As discussed earlier, the brain is active even during sleep. The brain’s neocortex and hypothalamus are involved in the processing and categorizing of information gathered throughout the day and consolidated as a memory. These processes occur more efficiently during the REM phase of sleep.
The REM phase begins only when all the muscles of the body are completely relaxed. However, relaxed muscles lead to the tongue to fall back on the epiglottis, blocking airways. Airflow is interrupted while breathing, causing the patient to wake up gasping for air.
This event is how sleep apnea can affect the quality of REM sleep. As a result, memory consolidation is hampered.
Patients with sleep apnea have difficulty recollecting what they learned during the daytime and experience problems learning and retaining new skills and information.
According to research studies, this may also lead to a significant impairment of procedural and verbal declarative memory.[5]
Oxygen Supply
The regular flow of oxygen is essential for the optimum functioning of the brain. Sleep apnea can cause breathing to get frequently interrupted, due to which the supply of oxygen to the brain tissues is affected.[6] As a result, the brain may face temporary yet multiple shortfalls in the availability of oxygen. Over time, these physiological patterns can cause brain damage, leading to the impairment of memory and compromised brain performance.[7]
Inefficient Healing
The body’s natural healing processes work more efficiently while we are sleeping. Poor sleep can affect these healing mechanisms. As a result, minor tears in brain tissues and exposure to toxins and free radicals lead to brain damage. The damage to brain tissues may progress considerably, affecting cognitive functions, like memory and attention span.
Alzheimer’s Disease
Research studies show that the risk of memory loss due to dementia and Alzheimer’s disease is higher in patients with sleep apnea.[8] A lack of continuous oxygen supply and inefficient healing processes may accelerate the brain’s degenerative changes, making a person prone to develop Alzheimer’s disease at a younger age. Also, memory loss associated with Alzheimer’s disease progresses faster in patients with sleep apnea, marking a significant link between memory problems and sleep disorders.
Change in Shape
A lack of sound sleep due to sleep apnea may alter the brain’s shape, which is one of the mechanisms by which this disorder can affect memory. A comparison of brain structures of patients with sleep apnea to healthy people confirms this theory.
Research studies have found that the part of the brain responsible for memory storage, or the mammillary bodies, is smaller by nearly 20% in patients with sleep apnea than in healthy participants, indicating reduced efficiency of the brain to store memories.[9]
Smaller mammillary bodies may also affect the brain’s memory recall functions and create difficulties in the academic performance and workplace productivity of patients with sleep apnea.[10]
Reduces Gray Matter
Multiple research studies have discovered that sleep apnea may decrease the gray matter in areas of the brain involved in memory processing and consolidation processes, suggesting why patients with sleep apnea often have a weak memory.[11] [12]
Diagnosis
A diagnosis is essential if you want to get the treatment you need to manage your sleep apnea. There are two options available, depending on your pre-existing conditions.
1. In-Lab Sleep Test: This test requires you to go to a sleep center to be evaluated.
2. Home Sleep test: A convenient way to get a diagnosis for those who are medically qualified. If you’re on oxygen or have heart failure, severe COPD, or conditions that have severe Co2 retention, your testing is best managed at a local sleep lab or center. MH Sleep Testing is a great option for home sleep testing.
Conclusion
Sleep apnea is associated with the reduced efficiency of the brain. It can affect memory by interfering with REM sleep and affecting the body’s healing processes. The long-term damage to the brain due to inefficient oxygen supply can further affect memory and even increase the risk of Alzheimer’s disease. It’s recommended that patients with sleep apnea seek appropriate medical intervention to improve their sleep quality and prevent a decline in memory.
References
- Spicuzza, L., Caruso, D., & Di Maria, G. (2015). Obstructive sleep apnoea syndrome and its management. Therapeutic advances in chronic disease, 6(5), 273–285. https://doi.org/10.1177/2040622315590318.
- Osman, A. M., Carter, S. G., Carberry, J. C., & Eckert, D. J. (2018). Obstructive sleep apnea: current perspectives. Nature and science of sleep, 10, 21–34. https://doi.org/10.2147/NSS.S124657.
- Eugene, A. R., & Masiak, J. (2015). The Neuroprotective Aspects of Sleep. MEDtube science, 3(1), 35–40. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4651462/
- Rasch, B., & Born, J. (2013). About sleep’s role in memory. Physiological reviews, 93(2), 681–766. https://doi.org/10.1152/physrev.00032.2012.
- Kloepfer, C., Riemann, D., Nofzinger, E. A., Feige, B., Unterrainer, J., O’Hara, R., Sorichter, S., & Nissen, C. (2009). Memory before and after sleep in patients with moderate obstructive sleep apnea. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 5(6), 540–548.
- Wallace, A., & Bucks, R. S. (2013). Memory and obstructive sleep apnea: a meta-analysis. Sleep, 36(2), 203–220. https://doi.org/10.5665/sleep.2374.
- Hoth, K. F., Zimmerman, M. E., Meschede, K. A., Arnedt, J. T., & Aloia, M. S. (2013). Obstructive sleep apnea: impact of hypoxemia on memory. Sleep & breathing = Schlaf & Atmung, 17(2), 811–817. https://doi.org/10.1007/s11325-012-0769-0.
- Andrade, A. G., Bubu, O. M., Varga, A. W., & Osorio, R. S. (2018). The Relationship between Obstructive Sleep Apnea and Alzheimer’s Disease. Journal of Alzheimer’s disease : JAD, 64(s1), S255–S270. https://doi.org/10.3233/JAD-179936.
- Kumar, R., Birrer, B. V., Macey, P. M., Woo, M. A., Gupta, R. K., Yan-Go, F. L., & Harper, R. M. (2008). Reduced mammillary body volume in patients with obstructive sleep apnea. Neuroscience letters, 438(3), 330–334. https://doi.org/10.1016/j.neulet.2008.04.071.
- Harper, R. M., Kumar, R., Ogren, J. A., & Macey, P. M. (2013). Sleep-disordered breathing: effects on brain structure and function. Respiratory physiology & neurobiology, 188(3), 383–391. https://doi.org/10.1016/j.resp.2013.04.021.
- Joo, E. Y., Tae, W. S., Lee, M. J., Kang, J. W., Park, H. S., Lee, J. Y., Suh, M., & Hong, S. B. (2010). Reduced brain gray matter concentration in patients with obstructive sleep apnea syndrome. Sleep, 33(2), 235–241. https://doi.org/10.1093/sleep/33.2.235.
- Macey, P. M., Kumar, R., Woo, M. A., Valladares, E. M., Yan-Go, F. L., & Harper, R. M. (2008). Brain structural changes in obstructive sleep apnea. Sleep, 31(7), 967–977.
