What a Yawn! What a Brain!
What is yawning?
According to the Oxford dictionary yawning is “a reflex act of opening ones mouth wide and inhaling deeply due to tiredness or boredom”.
It is a very familiar activity that we all engage in at times, particularly whilst studying, sitting through a boring movie or watching the clock on Friday afternoons anxiously waiting for that last lecture to end or work to finish! For many, yawning is seen as an unpleasant, bad mannered and an embarrassing waste of time; an evolutionary throwback from our ancestral roots that we haven’t yet been able to supplant. How many times have we found ourselves red faced when an uncontrolled yawn overpowers us during an important social function or whilst listening to a friend describing their latest overseas adventure! Yawning, believe it or not, has a number of useful roles to play in caring for our health – all related to our brain function.
Keeping it cool
In a study conducted in New York in 2007 it was suggested that yawning automatically causes the inhalation of fresh air to cool the brain and preserve cerebral effectiveness, much like a fan is used to cool a computer’s CPU. This action is known as the thermoregulatory theory of yawning and is important in maintaining our body’s homeostasis. It is proposed that this mechanism would come in to play when the brain temperature increases due to complex brain processing. That is, increased yawning would occur resulting in cooling the brain.
Yawning on waking up in the morning is a good response to have before we grab a coffee as it has a positive effect on our brain. When the physical process of yawning takes place it results the automated masseteric reﬂex of the jaw activating brain activity. When we are at rest or in a contemplative mood our brain enters a neutral or similar to a computer sleep mode. However, during this time a default mode network (DMN) maintains core brain activity. Yawning appears to unlock the DMN and put the brain back into gear. It does this by stimulating the locus coeruleus, which acts to boost brain alertness.
Egg heads rule
There has been recent studies into comparing yawning behaviours in humans and other mammals. Primates such as gorillas share many of the yawning habits as humans. A study in New York in 2016 examined a large sample of mammals that were recorded yawning on YouTube and compared the yawns. The study found that the length of time that an animal yawns is a good predictor of its brain size and complexity; primates were observed on average to have longer yawn patterns than other mammals such as dogs and cats.
Humans yawn for longer periods of time than other mammals and the study suggests that this is because human brains are larger and significantly more complex. In fact it is thought that the physiological impacts of yawning have an effect on the brain as a whole and can be used to stimulate the brain’s activity.
So I’m not being lazy when I yawn, I’m just exercising my brain.