Ask A Scientist

Are yawns contagious? 

Asked by: Rose Nguyen
School: St. John the Evangelist
Grade: 5
Teacher: Anu Rai
Hobbies/Interests: Playing the computer and iPod
Career Interest: Doctor, scientist 


Answer from Jessica Surdey

Instructor, Health and Wellness Studies

Research area: Stress, identity, self-esteem
Interests/Hobbies: Exercise, home renovation

There are many theories to explain why people yawn. However, they are all still theories. At this point, we do not fully understand the reason behind yawning.

Yawning is an involuntary reflex that involves the inhalation of air by the opening and stretching of the mouth and eardrums, followed by exhaling. Yawning is often accompanied by stretching of the body. This is called pandiculation. Humans yawn and so do animals, like dogs, chimpanzees, baboons and horses.

Yawning begins from the hypothalamus in the brain and is affected by neurotransmitter levels. Yawning is involuntary, which means that it is not something we can control. Some chemicals — both natural, like serotonin, or consumed drugs, like alcohol — can cause people to yawn more frequently. Scientists report that babies in their mother's wombs yawn in the first trimester. So, yawning starts very young and continues through life. Why do we yawn? There are several ideas and ongoing research to try an understand yawning:

• It’s caused by being tired, but this may be due to timing because an hour before bed or after we wake up is when we most frequently yawn • It gets more oxygen into the blood when carbon dioxide levels get too high • It cools down the brain • It increases alertness, and ease nervousness or performance anxiety • From an evolutionary perspective, it might be a herd instinct • Binghamton researchers looked into this and found that yawning actually cools down the brain

Why are yawns contagious? There are also several theories about this, including:

• Yawning symbolizes empathy and shows others that you relate to them. Interestingly, people with difficulty in social relations don’t "catch the yawn" at the same rate other individuals do. • It’s a form of social bonding and connection between groups. • Yawning is a shared experience that can help reduce stress throughout a group.

Different species can also experience contagious yawning. For example, my dog yawns after seeing me yawn!

You don’t necessarily need to see someone yawn in order to yawn — just hearing a yawn, watching someone yawn on TV, or reading about it can make you yawn, too! I have only been reading and writing the word "yawn," and it has caused me to yawn a lot

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Last Updated: 9/25/14