Yawning reduces the temperature of the brain.
Almost everyone yawns, but the reasons for this behavior are just beginning to be fully understood. Although yawning is often associated with tiredness, yawning does not actually signal the need for sleep.
Furthermore, research has indicated that yawning actually promotes alertness. Understanding the cause of yawning can also aid our comprehension of behavior in other animals as virtually all vertebrates appear to yawn in similar situations.
Thermo-regulation and Stress
Yawning seems to be triggered by heat and stress. Thermo-regulation, or purposeful normalization of body temperature, is necessary for avoiding hypothermia and hyperthermia and is exemplified by actions such as sweating and panting. Yawning, however, specifically reduces the temperature of the brain.
Dr. Andrew Gallup, a leading researcher on yawning, first delved into the connection between yawning and thermo-regulation in a 2007 study. Dr. Gallup found that when brain temperature rises by even less than one degree, yawning is stimulated to prevent slowing of reaction time and worsening of memory.
In the years since, Dr. Gallup has studied yawning in a variety of species and found that yawning is often prompted by stressful situations, which cause brain temperature to rise. Future studies may further clarify the purpose of yawning.
Why Is Yawning Contagious?
Yawning in one individual often sparks yawning in other members of a group, and this principle holds true even in non-human species. From other research by Dr. Gallup, contagious yawning has been found to aid alertness in groups during stressful situations.
The scientist found that when exposed to noise, parakeets in groups tended to experience contagious yawning while parakeets not exposed to the noise did not mirror the yawns of others as frequently.
When Is Yawning More Likely to Occur?
As might be expected from the research of Dr. Gallup, observers have noted that humans are most likely to yawn during stress and not necessarily during fatigue. In fact, yawning is not an uncommon sight among professional athletes before events.
Because a rise in brain temperature is the link between these situations and yawning, yawning is more likely to occur during the summer than during the winter.
Who Is Less Likely to Yawn Contagiously?
Most people are prone group yawning, but not all individuals are equally susceptible. Due to incomplete brain development, infants are less likely to yawn in response to seeing others yawn.
People with schizophrenia and autism are also less likely to experience contagious yawning due to defects in the empathy system of the brain, which normally prompts mirroring of behavior in others.