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Yawning: What Is It And How Is It Connected To Breathing?

We all yawn. In fact, fetuses begin yawning at around eleven weeks. On average, people yawn 5–10 times a day, although this can vary widely. I have had clients who yawn far more frequently: 10–15 times in an hour. So, what is yawning? Why do some people yawn so much? And what does yawning have to do with breathing?

Two aspects of yawning are the mechanical and the biochemical. Mechanically, yawning involves a deep inhalation (usually through the mouth), a stretching of facial muscles and eardrums, with a brief hold at the peak of the stretch, and a slow exhalation.

An early theory about why we yawn, now largely discounted, was that we yawn to expel excess CO2 or when our blood oxygen (O2) levels are low. It was hypothesised that a yawn brought in fresh O2 and expelled excess CO2. Research into that theory showed that subjects did not yawn more when O2 levels were low, or CO2 levels were high². Rather, when the levels of O2 and CO2 in the air changed, subjects altered the rate of their breathing to compensate. It has also been observed that people yawn in a variety of situations where blood gases are at normal levels.

While the purpose of yawning is not fully understood, the three main theories are that we yawn to:

• regulate brain temperature⁴

• change our state (a brain reset, e.g. from sleepy to alert)⁵

• communicate with others⁶.

However, excessive yawning can be seen in people who chronically overbreathe, which can lead to poor CO2 regulation. The causes of overbreathing vary, but culprits include medical conditions, stress, and anxiety. Overbreathing leads to poor CO2 regulation. When we overbreathe, the amount of CO2 drops below a normal, healthy level. The receptors in our brainstem that detect CO2 (indirectly via pH levels in cerebrospinal fluid) reset over time to respond to lower levels of that gas⁷. As a result, people with chronic overbreathing often feel an urge to yawn.

While there are many downsides to not having enough CO2 in your system, a critical issue is that CO2 is critical to controlling your blood pH. If you have too little CO2, your blood becomes more alkaline. The effects of that include:

• Blood vessels in the brain narrow, causing dizziness/lightheadedness/brain fog⁸

• Nerves are more likely to fire unnecessarily, causing pins & needles, numbness⁹

• Muscles become more excitable, leading to cramps and twitching¹⁰

• Less oxygen is released from blood into tissues (Bohr effect in reverse)¹¹

All of these negative outcomes can also lead to anxiety and panic attacks. Unsurprisingly, this is where breathing comes in.

Functional breathing ensures that our CO2 levels are balanced by resetting the baseline for our CO2 receptors and improving our tolerance to that gas. This leads to the blood pH levels returning to normal (pH 7.35–7.45 for those who are curious ¹². You can achieve a reset through a breathing programme that focuses on addressing your breathing biochemistry and specifically, CO2 intolerance.

The conclusion? Yawning is a normal reflex experienced by all of us. It can be a symptom of dysfunctional breathing and low tolerance to CO2. It is possible that yawning may perpetuate the cycle of overbreathing since each yawn can temporarily reduce our CO2 levels. Retraining the breath with a biochemical focus can restore the balance of our body’s chemistry, reduce yawning, and reduce the negative symptoms associated with overbreathing. So, if you think you are yawning a little more than you should, take note — it may just be your body telling you it’s time to improve the quality of your breathing.

References

1. Nattie, E. (1999). CO2, brainstem chemoreceptors and breathing. Progress in Neurobiology, 59(4), 299–331.

2. Provine, R. R., Tate, B. C., & Geldmacher, L. L. (1987). Yawning: No effect of 3–5% CO2, 100% O2, and exercise. Behavioral and Neural Biology, 48(3), 382–393.

3. Provine, R. R. (2005). Yawning. American Scientist, 93(6), 532–539.

4. Gallup, A. C., & Gallup, G. G. (2007). Yawning as a brain cooling mechanism: Nasal breathing and respiratory cooling. Medical Hypotheses, 69(2), 440–448.

5. Gallup, A. C. (2014). Yawning and thermoregulation. Physiology & Behavior, 130, 145–148.

6. Deputte, B. L. (1994). Ethological study of yawning in primates. 1. Quantitative analysis and study of causation in two species of Old World monkeys. Ethology, 98(3–4), 221–245.

7. Gardner, W. N. (1996). The pathophysiology of hyperventilation disorders. Chest, 109(2), 516–534.

8. Raichle, M. E., & Plum, F. (1972). Hyperventilation and cerebral blood flow. Stroke, 3(5), 566–575.

9. Lum, L. C. (1981). Hyperventilation and anxiety state. Journal of the Royal Society of Medicine, 74(1), 1–4.

10. Gardner, W. N. (1996). The pathophysiology of hyperventilation disorders. Chest, 109(2), 516–534.

11. Laffey, J. G., & Kavanagh, B. P. (2002). Hypocapnia. New England Journal of Medicine, 347(1), 43–53.

12. Guyton, A. C., & Hall, J. E. (2016). Textbook of Medical Physiology (13th ed.). Elsevier.

Disclaimer

This blog is for informational purposes only. It is not medical advice. Always consult a healthcare professional for personalized guidance and treatment.