The accepted (but inaccurate) explanation for yawns, which also exist in fetuses and the animal world, is that yawning is intended to cool the brain.
The approach I present here for the first time offers a different conception than the conventional one for the widespread phenomenon of yawning.
- Energy is a critical resource in the living world! Nature is built to conserve vital energy. It was initially thought that yawning was intended to pump more oxygen into the lungs, but this theory was wrong. The explanation that yawning is intended to cool the brain indirectly is plausible, but the answer is incomplete and does not provide a broad view.
- If the explanation that yawning is intended to cool the brain were the full explanation, then when we have a high fever, we would yawn endlessly. Yawning usually lasts a few seconds and cannot cool the brain significantly. Lowering the brain's gear takes loads off it and indirectly also cools it down, but the original explanation, accepted in the literature, is incomplete.
- Fatigue without physical effort is often metabolic fatigue, in which the liver and kidneys are under high loads. In such a situation, the supply of nutrients to the brain is impaired; therefore, when we are tired, we yawn. A heavy meal weighs on the liver and makes us yawn even in the middle of the day.
Our brain is constantly occupied with a subconscious activity, which consumes considerable resources. (Not just calories)
The need to "lower a gear" exists when the brain detects a situation in which it may not work effectively.
- Yawning happens, especially when we are bored or tired. The fact that yawning is a contagious phenomenon comes from a completely different explanation. We tend to imitate others to save valuable resources of the brain. If you see someone yawning and you feel bored, you will probably imitate the action without activating a thought mechanism, an energy grabber.
- I suffer from constant fatigue as a person with cirrhosis of the liver. I'm busy writing and thinking constantly, and I am mainly yawning when I'm exhausted.
The liver-kidneys and the brain utilize over 50 percent of the body's energy at rest. When we are exhausted due to metabolic fatigue, sometimes after a heavy meal (which burdens the metabolic system), the brain "lowers a gear" through yawning or a series of yawns to save energy resources.