Yawning might be a natural brain thermoregulation mechanism. This hypothesis is supported by experiments with cold compresses.
Yawning
Yawning is traditionally associated with fatigue or boredom, but some studies suggest it may serve another function – helping to cool the brain. Experiments where people yawned significantly less when a cold compress was applied to their forehead support this hypothesis.
This was reported by Space Daily.
This assumption underlies the so-called thermoregulatory theory of yawning, or the brain cooling model. It states that yawning may partially function to regulate brain temperature. The first direct evidence supporting this hypothesis was published in 2007 by Andrew Gallup and Gordon Gallup in the journal Evolutionary Psychology.
During the study, the researchers conducted two experiments on contagious yawning – a phenomenon where a person involuntarily starts yawning upon seeing someone else do it.
Thirty-three students from the University of Albany participated in one of the experiments. While watching videos of people yawning, they held compresses of different temperatures on their foreheads: cold (4°C), warm (46°C), or room temperature.
After the experiment concluded, it was found that among participants with warm and neutral compresses, 41% yawned. In contrast, in the group with the cold compress, this figure was only 9%. According to the study’s authors, this indicates a connection between cooling and a reduced frequency of yawning.
A similar trend was observed during the first experiment. Participants were divided based on their breathing method. Almost half of the people who breathed through their mouths or received no specific instructions yawned. Meanwhile, no cases of yawning were recorded among those who were instructed to breathe through their noses. The researchers suggested that nasal breathing might also contribute to brain cooling.
At the same time, the authors emphasize that the study only examined contagious yawning, not spontaneous yawning. This format was chosen because it is easier to replicate in a laboratory setting using video recordings. Therefore, the obtained results do not imply that both types of yawning share the same mechanism.
Subsequently, the researchers continued to test this hypothesis. They obtained similar results in experiments with budgerigars and rats, where the frequency of yawning also depended on the ambient temperature.
Another study involving humans was published in 2019. This time, cold, warm, and neutral compresses were applied not to the forehead, but to the carotid artery area on the neck. The results again showed that cooling was associated with fewer instances of contagious yawning. The researchers used thermal imaging equipment to monitor temperature changes.
Despite these findings, the scientists do not consider the theory definitively proven. They note that most studies were conducted on small groups of participants, and a significant portion of the work belongs to the same group of authors.
There is another explanation for this phenomenon. American researcher Robert Provine, who studied yawning for many years, considered it primarily a manifestation of changes in the body’s arousal level. In his opinion, contagious yawning is more related to social behavior and people’s tendency to imitate each other than to thermoregulation.
Recall that earlier, scientists were able to preserve the viability of human eye retina for the first time for such a long period that it responded to light even 10 hours after the donor’s death.
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