medicalnewstoday.com
 
Why Do We Yawn?
User avatar
Curated by
cdteliot
3 min read
3,338
53
Yawning, a common reflex that lasts about 4-7 seconds, remains a mysterious phenomenon despite centuries of scientific inquiry. While theories abound, from brain temperature regulation to social bonding, researchers have yet to reach a consensus on the exact purpose of this involuntary action that begins in the womb and continues throughout our lives.

 

The Brain Cooling Theory

wsj.com
wsj.com
The brain cooling theory of yawning has gained substantial scientific support in recent years. This hypothesis posits that yawning serves as a thermoregulatory mechanism to cool the brain through increased blood flow and heat exchange with inhaled air.
1
Studies have demonstrated that yawning frequency is influenced by ambient temperature, with an optimal "thermal window" for yawning around 20°C.
2
Yawning decreases at extreme temperatures, both hot and cold, further supporting its thermoregulatory function.
3
Researchers have found that the duration of yawns correlates positively with brain size and neuron count across mammalian species, suggesting that animals with larger and more complex brains require longer yawns to achieve the same cooling effect.
4
This evidence, combined with observed physiological changes during yawning such as increased blood flow to the head and face, provides strong support for the brain cooling theory as the primary explanation for this ubiquitous behavior.
1
ncbi.nlm.nih.gov favicon
medicalnewstoday.com favicon
pubmed.ncbi.nlm.nih.gov favicon
4 sources

Circulatory Effects of Yawning

calmclinic.com
calmclinic.com
The physical act of yawning triggers significant circulatory changes in the body, supporting its potential role in brain cooling. Studies have shown that yawning causes a marked increase in heart rate, with one investigation finding a significant rise at the peak of yawning and for several seconds afterward compared to baseline levels
1
.
This acceleration in heart rate is accompanied by increased blood flow to the head and face regions. The contraction and relaxation of facial muscles during a yawn enhance facial blood flow, potentially aiding in heat dissipation through emissary veins
1
.
Additionally, yawning leads to an increase in skin conductance, indicating heightened arousal similar to that induced by stimulants like caffeine
1
.
These physiological responses collectively suggest that yawning may facilitate the removal of warm blood from the brain while introducing cooler blood, thus contributing to temperature regulation in the central nervous system
2
1
.
ncbi.nlm.nih.gov favicon
medicalnewstoday.com favicon
2 sources

Psychological and Social Aspects

somnowell.com
somnowell.com
Contagious yawning has long been associated with empathy, but recent research suggests this link may be more complex. While some studies have found a correlation between empathy and susceptibility to contagious yawning, others challenge this connection. A study published in i-Perception found that perceptual sensitivity, rather than empathy, was more closely related to contagious yawning in non-clinical populations
1
.
However, the phenomenon does appear to have social aspects. Auditory contagious yawning (triggered by hearing but not seeing a yawn) is highest between friends and family members, suggesting a social bonding component
2
.
Yawning may also serve as a non-verbal communication tool, potentially signaling tiredness or boredom and helping to synchronize group behavior
3
.
Despite these social theories, the exact relationship between yawning, empathy, and prosocial behavior remains unclear and requires further research
4
.
sciencedaily.com favicon
frontiersin.org favicon
ncbi.nlm.nih.gov favicon
4 sources
Related
What are the main theories explaining the physiological significance of yawning
How does contagious yawning differ across various species
What are the potential evolutionary benefits of yawning
How does brain activity change during a yawn
Can yawning be linked to stress relief or relaxation
Keep Reading
Quantum Entanglement in the Brain
Quantum Entanglement in the Brain
The concept of quantum entanglement in the brain, where particles become interconnected in ways that could influence consciousness and cognition, has sparked intense scientific debate and research. While some researchers propose that quantum processes might explain complex brain functions, others argue that the warm, wet environment of the brain is unsuitable for maintaining quantum states.
100,357
What Causes Déjà Vu?
What Causes Déjà Vu?
Déjà vu, the eerie sensation of having experienced a current situation before, is a common phenomenon that has long puzzled scientists and researchers. According to Scientific American, this mysterious feeling may arise when parts of the brain responsible for recognizing familiar situations are activated inappropriately, offering a glimpse into the intricate workings of our memory systems.
8,294
Why Does Ice Cream Give You a Brain Freeze?
Why Does Ice Cream Give You a Brain Freeze?
Brain freeze, also known as ice cream headache, is a brief but intense pain in the head caused by consuming very cold foods or drinks too quickly. According to researchers at Harvard Medical School, this phenomenon occurs when the cold temperature rapidly constricts blood vessels in the roof of the mouth, triggering a chain reaction that leads to the dilation of brain arteries and activation of pain-sensitive nerves.
3,319
Why Do We Get Hiccups and How Can You Stop Them?
Why Do We Get Hiccups and How Can You Stop Them?
Hiccups occur when the diaphragm, a muscle between the lungs and stomach, involuntarily contracts, causing a sudden intake of air that is quickly stopped by the closure of the vocal cords. While the exact cause isn't always clear, common triggers include eating too quickly, carbonated beverages, and sudden excitement.
4,076