( ^ In other words: Why We Yawn and Get Brain-Freezes)
-A Human Anatomy paper gone Haywire, by Miranda H.
Sometimes the body does things that we don’t really understand; often we don’t think to wonder why. Yawning is one of these things. Why do we yawn? I’m sure you have noticed that when you see someone else yawn, suddenly, you are overcome with the need to yawn as well. Why is this the case? Also, what is a ‘brain-freeze’? What causes the rush of pain after eating/drinking something especially cold? The ‘unexplained’ intrigues me, as hopefully, it does you as well.
The definition of a yawn is: ‘To open the mouth wide with a deep inhalation, usually involuntarily, from drowsiness, fatigue, or boredom’ but recent studies have started to discover that this may not be totally correct. Although we would like to have a set cause for yawning and what triggers it, there isn’t just one, rather, there are quite a few theories as to the primary reason. None of these, however, have been empirically proved.
Recent studies have shown that yawning may be connected to the cooling down of the brain by breathing in a large amount of air. Did you know that our brain temperature is different from our body temperature? The brain burns about 20% of the calories we consume daily, as a result, it generates heat. Since the brains of mammals function best within a slim temperature range, many think yawning may be our bodies’ way of cooling it down. In 2007 Scientists had a group of people watch videos of yawning and discovered that, when cold-packs were applied to the forehead throughout, it nearly eradicated contagious yawning.
Interestingly enough, another study has shown that peoples yawning differ from season to season; hence, yawning may very well be thermoregulatory behavior. Subjects were exposed to two seasonal temperatures of desert climates, winter at around 70 degrees, and early summer at around 98 degrees. Upon showing the subjects pictures of people yawning, there was a significant difference in regards to the amount of yawning, winter: 45%; summer: 24%. Participants were more likely to yawn in the milder environment after extended periods of time outside, while lengthy exposure to temperatures at or above body temperature was related with reduced yawning; an overheated brain gets little relief from taking in air that is warmer than body temperature.
Have no fear, though, the most common idea that yawning is a result of fatigue isn’t completely off. All these observations would explain why we yawn when tired, Sleep deficiency increases brain temperature. Another explanation for this phenomenon is that when our blood contains increased quantities of carbon dioxide, it becomes in need of the inflow of oxygen (or expulsion of carbon dioxide) that a yawn is said to provide. Nervousness has also been suggested as a possible reason; uneasiness often indicates the awareness of an approaching need for action. Circumstantial evidence proposes that yawning benefits the increase of the state of alertness in a person.
As for why yawning is contagious, scientists have speculated that it is a way to signal to others in a group to stay alert and ready in the event of outside attacks, at least in cases of dog packs. Keep in mind, though, that all of these reasons discussed so far are only hypothesis and theories. We may never know exactly what the reason, since it was fashioned by the most magnificent and omnipotent creator.
Brain-freezes, what’s up with those, right? You’re basking in the delicious enjoyment of your chocolate milkshake, when out of nowhere you are interrupted by a searing pain in your forehead. What causes this agonizing interruption, you ask? Well, these Brain-freezes, otherwise known as ‘ice-cream headaches’, result from the intake, especially quick intake, of cold foods. The cold substance, in contact with the roof of the mouth (palate), or in swallowing it, brings about this cranial discomfort in about ten seconds. The sudden variation in temperature in the palate causes blood vessels to rapidly swell in an effort to warm the region back up. The increase of blood vessels activates pain receptors, which escalate sensitivity to further pain and produce inflammation. This happens while they are sending signals to the brain through the trigeminal nerve (pictured here, the trigeminal nerve is in yellow) to alert it of the quandary. Because the trigeminal nerve senses facial pain as well, the brain deduces that the pain signal is coming from the forehead. This occurrence is called “referred pain”, which is an easy way of saying, “pain perceived at a location other than the site of the painful stimulus.” This rise in blood volume and subsequent growth in size in the anterior cerebral artery (supplies oxygenated blood to parts of the brain) is thought to bring about the pain related with ice-cream headaches.
To help relieve the aching, some doctors propose pressing the tongue against the roof of the mouth to warm the area, or tipping the head back for about 10 seconds.
There you have it, two events that happen quite frequently but we don’t often ask why. Just keep in mind, you could be in danger of rupturing an artery while diving into your ice-cream wonderland- but what a way to go. ;)
