Why is Yawning Contagious?

yawningThere you are, in a crowded train, long day at work, minding your own business and looking forward to getting home. Then you feel it, growing in your mouth and before you know it, out pops a yawn. Then one by one, like a set of falling dominos, the other commuters start yawning. So why is yawning so contagious?

Studies of Yawning

The scientific study of yawning now has a name, “chasmology.” Since the 19th Century, yawning was thought to be a reaction to hypoxia (a deficiency of the amount of oxygen reaching the bodily tissues) which triggered a rush of oxygen, flushing out carbon dioxide. However recent studies have shown that yawning has no effect on the body’s carbon dioxide or oxygen levels.

Some US researchers are saying that yawning, rather than being seen as being tired, is designed to keep us awake, to cool the brain so it is more efficient. One study found that more people were likely to yawn during winter months rather than summer months. This is due to the fact that in the summer the air is warmer and has a lesser impact on brain temperature. Additionally, when the jaw stretches during a yawn, the blood flow to the brain is increased and in return, it is believed that this increases the cooling effect.

Another recent study showed that when people had cold packs on their heads, the rate of contagious yawning drastically decreased, compared to the 40 to 50% for those at room temperature or holding a heated pack on their heads.

Some modern theories about “mirror neurons” may play a part, these mirror neurons in our brains regulate us when we are being copied and influence us to copy others, so we yawn if we see someone else doing it.

It is an involuntary action and most animals including fish and even rabbits yawn. It is linked behind a theory that by keeping us awake it is behind the ancient tribal need to stay awake in groups to detect and avoid danger.

Or perhaps it was used in social behaviour as a way of forming a bond with the rest of the group. (Did you feel that in the train carriage?!) It is a common fact that contagious yawning is more common among those closely acquainted, for example family members or couples. So is yawning linked to empathy? Is it and has it evolved as a form of social communication? Some theories show that you are more likely to catch a yawn if you are socially empathetic. An interesting aspect was a study conducted with autistic children who did not yawn more when shown videos of yawning people, further backing the empathetic research of contagious yawning.

TIRED yawningIt is said in one study that if you wish to spot a psychopath, then yawn at them. Scientists have found that the more psychopathic traits people have, the less likely they are to be effected by contagious yawning. Again this appears to further agree with the empathetic roll to contagious yawning.

But what is it in our subconscious behaviour that makes us want to yawn when we see someone yawning and even hearing someone yawn. Even thinking about yawning can make us yawn – between 40 to 60% of people who watch videos of or hearing the sound of yawning end up joining in.

There are various theories. It has been suggested by some that yawning is an “unconscious herding behaviour” and a subtle way of communicating. Others suggest that it was a way of communicating their alertness to coordinate sleeping times.

Yawning has been shown to increases blood flow to the brain. In addition, yawning is sometimes accompanied by the need to stretch joints and muscles. (Known as stretch-yawn syndrome or pandiculation) Could it therefore be a survival tool, an evolutionary tool to tell the body it must be on alert? Stress has also been shown to produce yawning, from students about to take an exam or nervous people about to take a parachute jump.

During the First World War, troops were shown to yawn when waiting for the whistle to “send them over the top” and charge the enemy. This could also show a link between alertness and a contagious theory. One study stated the presence of certain brain chemicals such as dopamine and serotonin are more likely to make us yawn. Being tired, tense tends or stressed has a tendency to increase the yawn producing chemicals and decrease the level of endorphins that are in your body.

For pack animals it makes sense for yawns to be contagious as it gives benefit for the increased alertness and be able to act quickly to avoid danger.

yawningAge could also play a part in contagious yawning. One study has shown that people who are younger are more at risk of “catching” another person’s yawn than older people. However scientists couldn’t explain why older people are less likely to catch another’s yawns. Neither was there a connection between yawning and intelligence, giving some researchers to believe that yawning is inherited in the hope that gene codes for contagious yawning could highlight new treatments for those who have mental health disorders.

One very clever Coffee business utilised contagious yawning by showing a billboard of a person yawning (With a sensor that the more people were passing the yawn became wider and wider) with the underlying theme that if people thought they were tired they would consider drinking coffee to wake up. The advert asked, “Did you yawn too? Time for coffee” A great way of converting contagious yawning into sales!

Another humorous use of contagious yawning was repeated in blogs during the “Planet of the Apes” films. Should you be about to be attacked by an ape, the last resort would be to yawn at it. Hopefully the ape would be under the contagious yawning philosophy and would need to yawn, giving you the opportunity to escape!

But the truth? We are still not 100% sure why we yawn, scientists and researchers continue to study this phenomena and no doubt one day we will find the answer. It is a reminder to us how mysterious human beings are.