A 2010 study published in the journal, Frontiers in Evolutionary Neuroscience, suggests that a yawn may not be an attempt to give the brain more oxygen.
Rather, the new science suggests that yawning has a cooling effect on the brain. Researchers showed that yawning was triggered when the brain temperature increased rapidly by only 0.18 degree Fahrenheit. When the brain temperature fell, the yawning stopped. (1)
According to the research, it seems that if the outside air is somewhat cooler than the brain temperature, the body may use a yawn to drive cooler air in to chill down the brain.
Interestingly, the brain tends to get hotter and provokes more yawning in the following conditions:
- Stress (2)
- Sleeplessness (2)
- In the summer (1)
- Anxiety (2)
- Migraines (2)
- Drowsiness (2)
- Multiple Sclerosis (2)
Researchers believe that many neurological imbalances may be due to a dysfunction in the regulation of the brain temperature. (2)
Ayurveda addresses this with one of its ancient folk remedies for migraine headaches called, “cold to the head, heat to the feet.” I have used this technique successfully for years, and now it is supported by science, which suggests that migraines may be due to an increased and sustained brain temperature.
I also found it interesting that the average rate of yawning increases in the summer, when the outside temperature rises and the brain may tend to overheat. Ayurveda suggests breathing techniques, or pranayama exercises, to help cool the brain for certain heat-related, or pitta, imbalances. One study suggests that nasal breathing may cool the brain temperature and reduce the incidence of yawning. (3)
Of course, I am a big fan of using nasal breathing versus mouth breathing during exercise. In our study in my book, Body, Mind and Sport, we found that nasal breathing created a significant increase in alpha brain waves indicating a calming, or even a meditative state during exercise. (4)
Interestingly, there is also a yoga breathing technique called, Sheetali, or Cooling Breath, where you inhale through a rolled tongue into the mouth and exhale through both nostrils. This is purported to cool excess brain and body heat.
According to Ayurveda, many people with pitta body types have trouble dissipating the heat out of the body, and since heat rises, this can often affect the brain and mood. Of course, this accumulation of heat is worse during the summer months for pitta types, who may benefit from becoming good at nasal breathing.
It is interesting to learn that the concept of brain heat, which Ayurveda considers a pitta condition, is being verified by a wealth of recent studies.