A yawn is generally defined as the involuntary act of opening one's mouth wide and inhaling deeply due to tiredness or boredom. In humans, yawning most often occurs in adults immediately before and after sleep, and very often in response to seeing another person yawn.
We may also yawn by seeing a photo of a yawning person, or even reading or thinking about a yawn.
Yawning is very commonly associated with being tired, stress, overwork, lack of stimulation and boredom. Studies show that the average adult will yawn about 10-to-15 times every day.
Dr. Jim Surrell
It is also interesting to note that even an unborn child in the womb will yawn. It is not only humans that yawn because snakes, fish, mice, cats, dogs and most animals also yawn.
The reason why people and animals yawn is not well understood. Approximately 20 physiological reasons for yawning have been proposed by various scientists, but there really is little scientific agreement as to why we yawn.
As noted above, the average person will yawn about 10 to 15 times in one day, and it is also estimated that human beings will yawn about 250,000 times in the average human lifespan. The average length of time of a single yawn is about six seconds.
One prominent theory is that yawning may be directly linked to a warmer temperature in the brain. In other words, a yawn may be an attempt on the part of the body to cool the brain.
Regarding yawning and brain temperature, National Geographic reported on some interesting research that demonstrated that the open-mouthed yawn causes more air flow near the brain with the effect of lowering the brain temperature.
One study found that people were more likely to yawn during the winter, when the exterior air is much cooler, and less likely to yawn in the summer, when yawns won't do much to bring cold air into the body's upper airway to help cool the brain.
Additional research has also recently shown that increases in brain temperature are noted before yawning and decreases in brain temperature occur almost immediately after yawning.
Yawning is often described as two different types, either as 1) spontaneous, or as 2) contagious. The definition of a spontaneous yawn is a yawn that happens when someone is tired or perhaps just bored.
Spontaneous yawning is actually first observed in unborn children in the womb, while contagious yawning doesn't begin until a child is about 4-years old.
The second type of yawn is defined as a contagious yawn. This contagious yawning occurs in humans as a response to seeing, hearing, reading about, or even thinking about yawning.
It is estimated that about 70 percent of people will yawn themselves when they see another person yawn. Studies have also found that certain individuals are more susceptible to this contagious type of yawning than others.
Some of the beneficial effects of yawning include cooling the brain, stretching and exercising facial and upper body muscles, expanding the lungs to full capacity, increasing oxygen to our brain and bloodstream while helping to remove carbon dioxide from our lungs. So, go ahead and have a good yawn because it is a very natural and healthy thing to do.
Now that I think about it, I must have had at least 50 good yawns while researching and reading so much about yawning in preparation for this latest "Talk With the Doc" Mining Journal column!
Yes, yawning truly is contagious!
Editor's note: Dr. Jim Surrell, author of "SOS (Stop Only Sugar) Diet," has his practice at the Digestive Health Clinic at Marquette General Health System. Requests for health topics for this column are encouraged.