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Breathing impacts the brain's waste removal system (glymphatic system)

Updated: Mar 28

MRI brain

This is one very important cause of fragmented sleep that we are not discussing,

In the body the lymphatic system is a system of thin tubes and lymph nodes (commonly nicknamed glands) which have a critical role in our immune system, removing waste products and excess fluid. You may have experienced swollen glands (lymph nodes) during an infection and noticed after the infection the glands shrink.

The brain cannot contain lymph nodes because swollen glands would increase brain pressure to dangerous levels as the hard bony skull cannot expand. Scientists in recent years have discovered how the brain removes waste products which has been named the glymphatic system. There is still lots to be learnt about this system.

The research shows the glymphatic system becomes active when we are asleep, especially in the deep stages of sleep.

It appears the glymphatic system is triggered into action when noradrenaline levels fall and in particular when we enter the deeper stages of sleep. The brain relatively shrinks so there is more space for the fluid surrounding the brain (cerebrospinal fluid: CSF) and the fluid in between the brain cells (interstitial fluid). This allows the CSF and interstitial fluid to move more freely in order to remove waste products such as amyloid-β which is thought to be a dementia promoting protein.

Unfortunately, if an individual has sleep disordered breathing (SDB) the noradrenaline levels remain higher than someone who is breathing normally whilst asleep. SDB is a spectrum that includes increased resistance to airflow through the upper airway, heavy snoring, marked reduction in airflow (hypopnea), and complete cessation of breathing (obstructive sleep apnoea: OSA). In SDB during deep sleep the airway may become blocked or the resistance to the air entering and leaving may become too high it triggers a micro-arousal taking the individual out of deep sleep to allow the individual to breathe. The individual may wake up or may be unaware of the micro-arousal. Both of these mechanisms reduce the effectiveness of the glymphatic system to remove waste products from the brain.

In one small study (1) of 24 individuals with OSA and 24 controls dysfunction of the glymphatic system was found in the patients with OSA. In addition, glymphatic system dysfunction was consistent with OSA severity. The findings seem to explain the effects of OSA on increased risk of developing dementia and highlight the importance of OSA treatment.

Another small study (2) of 59 OSA patients (24 were female) and 62 controls (28 were female) demonstrated abnormal glymphatic system function may contribute to increased risks for Alzheimer's disease.

The Wisconsin Sleep Cohort Study demonstrated that there is a 3 times greater risk of moderate or worse OSA in post-menopausal women compared to pre-menopausal women. (3) Women with OSA are less likely to report snoring or witnessed gaps in breathing (apnoea) but are more likely to complain of daytime fatigue, lack of energy, insomnia, morning headaches, mood disturbance and nightmares compared to men (4).

The foundation of improving SDB is efficient breathing during wakefulness so the individual is breathing efficiently during sleep. Improving breathing efficiency with breathing re-education consists of two aspects. The first is ensuring the airway is open, strong and combined with nasal breathing. The second is ensuring the breathing volume matches the requirements of the body (avoiding over breathing), using the correct breathing muscles, slowing the speed of breathing to influence the autonomic functioning of the body and bring calmness to the mind. If you would like me to be your guide on improving breathing efficiency click for more information on my breathing re-education programmes.

In my conversation with Liz Earle MBE we discussed the importance of breathing efficiently and how this can be improved. Click here to listen to our conversation.

Nasal breathing whilst asleep is crucial to efficient breathing. Teaching your body to nasal breathe whilst awake will make it more likely you will nasal breathe whilst asleep however if you are mouth breathing whilst asleep your body may need to be re-educated to break this habit. There are various products available to keep the mouth closed whilst asleep. The product I have used is called MyoTape® (5% discount code available using this link and the code LOUISEOLIVER5) that can help you retrain your body to nasal breathe whilst asleep. MyoTape® does not cover the mouth and is available in small, medium, large size and for beards (Amazon links). I used the large size. (To help support my work, in particular the information I provide without cost, I am linked with affiliate programmes. Click to read my affiliate disclosure). Instead MyoTape® is placed around the mouth and gently brings the lips together with a light, elastic tension that helps to maintain lip closure and nasal breathing. I believe using a product that surrounds the mouth is safer so the individual can breathe using the mouth if needed. It is sensible to get used to wearing the product whilst awake and when you are ready start wearing it whilst asleep. Do not use this product if under the influence of alcohol or sedative drugs. It takes around 3 months of daily use to retrain the nerve circuits, so this becomes a natural unconscious habit. However, getting the mouth closed whilst asleep is only one aspect of efficient breathing.

I would recommend speaking to your health professional if you still have symptoms of SDB after 3 months of working on improving your breathing efficiency. If an individual is diagnosed with OSA and treated with a continuous positive airway pressure (CPAP) machine nasal CPAP is more effective and better tolerated than full mask CPAP. (5) An individual generally needs to be a nasal breather to use a nasal CPAP machine therefore in my opinion trying to re-educate the body for 3 months to nasal breathe whilst awake, asleep and moving is sensible before embarking on a sleep study.

How we breathe matters, especially during sleep as it impacts the ability of the brain to remove waste products (glymphatic system). However we can change how we breathe.

(1) Lee HJ, Lee DA, Shin KJ, Park KM. Glymphatic system dysfunction in obstructive sleep apnea evidenced by DTI-ALPS. Sleep Med. 2022 Jan;89:176-181. doi: 10.1016/j.sleep.2021.12.013. Epub 2021 Dec 28. PMID: 35030357.

(2) Roy B, Nunez A, Aysola RS, Kang DW, Vacas S, Kumar R. Impaired Glymphatic System Actions in Obstructive Sleep Apnea Adults. Front Neurosci. 2022 May 6;16:884234. doi: 10.3389/fnins.2022.884234. PMID: 35600625; PMCID: PMC9120580.

(3) Young T, Skatrud J, Peppard PE. Risk factors for obstructive sleep apnea in adults. JAMA. 2004 Apr 28;291(16):2013-6. doi: 10.1001/jama.291.16.2013. PMID: 15113821.

(4) Saaresranta T, Anttalainen U, Polo O. Sleep disordered breathing: is it different for females? ERJ Open Res. 2015 Nov 3;1(2):00063-2015. doi: 10.1183/23120541.00063-2015. PMID: 27730159; PMCID: PMC5005124.

(5) Genta PR, Kaminska M, Edwards BA, Ebben MR, Krieger AC, Tamisier R, Ye L, Weaver TE, Vanderveken OM, Lorenzi-Filho G, DeYoung P, Hevener W, Strollo P. The Importance of Mask Selection on Continuous Positive Airway Pressure Outcomes for Obstructive Sleep Apnea. An Official American Thoracic Society Workshop Report. Ann Am Thorac Soc. 2020 Oct;17(10):1177-1185. doi: 10.1513/AnnalsATS.202007-864ST. PMID: 33000960; PMCID: PMC7640631.

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