Why You Yawn So Much
When You're Anxious

What yawning actually is

Mechanically, a yawn involves a deep inhalation, usually through the mouth, a stretching of the facial muscles and eardrums, a brief hold at the peak of the stretch, and a slow exhalation. Fetuses begin yawning at around eleven weeks. It is one of the oldest and most universal reflexes we have.

An early theory held that we yawn to expel excess CO₂ or when blood oxygen levels drop. That theory has since been largely discounted — research showed that subjects didn't yawn more when oxygen was low or CO₂ was high, and that people yawn in many situations where blood gases are completely normal. The current leading theories suggest we yawn to regulate brain temperature, to change our state from one alertness level to another, or to communicate with others around us.

So yawning is normal. But excessive yawning — significantly more than average — is something worth paying attention to.

The overbreathing connection

Excessive yawning is associated with chronic overbreathing. When we breathe more than our metabolic needs require — which stress and anxiety both drive — CO₂ levels in the blood drop below their healthy range. The brainstem receptors that detect CO₂ gradually reset to respond to these lower levels, and over time the body becomes sensitised to even normal amounts of CO₂, treating them as excess and driving the urge to breathe it out faster.

One of the ways this manifests is as a persistent urge to yawn. Each yawn is a large mouth-breathing inhalation followed by an exhalation — a pattern that temporarily lowers CO₂ further. So in a real sense, yawning associated with dysfunctional breathing can perpetuate the very cycle it seems to be responding to.

Why low CO₂ matters more than most people realise

CO₂ is not simply a waste gas. It plays a critical role in maintaining blood pH, and when levels drop too low, the blood becomes more alkaline. The physiological consequences of this include:

• Blood vessels in the brain narrowing, causing dizziness, light-headedness, and brain fog
• Nerves becoming more likely to fire unnecessarily, producing pins and needles or numbness
• Muscles becoming more excitable, leading to tension, cramps, or twitching
• Less oxygen being released from blood into tissues — the Bohr effect working in reverse

All of these effects can amplify anxiety and, in some cases, trigger panic attacks. The body is in a state of low-grade physiological alarm even when nothing externally threatening is happening.

What breathwork does about it

Functional breathing addresses excessive yawning by resetting CO₂ tolerance — gradually retraining the brainstem receptors to be comfortable with healthy CO₂ levels again. This is done through slow, light nasal breathing and, over time, specific CO₂ tolerance exercises. As tolerance improves, the urge to yawn excessively reduces, blood pH returns to its normal range, and the associated symptoms, brain fog, anxiety, muscle tension, begin to ease.

If you find yourself yawning frequently, particularly at rest or during low-intensity activities, it is worth considering whether your breathing patterns may be contributing. It is a small signal that is easy to dismiss, but it points to something worth addressing.