Saturday, September 15, 2007

Why do we yawn, and is yawning really contagious?

You see, hear, read about, or think about someone yawning and now you want to yawn. Everyone yawns - babies, adults, teenagers, even animals! Most people relate yawning with fatigue, boredom, or drowsiness. But sometimes, regardless of how awake or stimulated you are, you can yawn simply because you observed someone else yawning. If this describes you, then you have just caught a yawn.

Yawning is an involuntary action. This means that we yawn without thinking about it, which is similar to when we breathe. The average duration of a yawn is 6 seconds. When we yawn, we open our mouths wide and breathe in deeply to take in as much air as possible. The inhaled air fills our lungs and expands them to capacity. Then some of the air is blown back out.

While there is no proven scientific explanation for why we yawn, there is thought that yawning is like stretching - both yawning and stretching increase blood pressure and heart rate, and they both flex muscles and joints. Evidence for relating yawning to stretching stems from trying to prevent a yawn from occurring. Have you ever felt a yawn coming and tried not to yawn? If so, you probably clenched your jaws shut and found it difficult to stop the yawn. Some researchers also proposed that yawning is used to cool the brain. For instance, people were observed to yawn more often in warm rooms, compared to when they were in colder rooms. Others think that yawning is a means of communication, which has evolved since our ancestors. Yawning could have been used as a signal to the other group members. However, none of these theories have actually been proven making yawning still one of the greatest mysteries.

So, have you yawned at all since you have read this?

Little Lion Experiment:

Although the cause and purpose of yawning is not understood, yawns seem to follow a daily cycle. This means that most people yawn around the same time of day everyday. While the actual times that people yawn can vary depending on the individual, most people tend to yawn soon after waking up and also about an hour before bedtime. This experiment will help you determine your yawning cycle.

Items Needed:

  • Paper
  • Pencil
  • A clock or watch


  1. On your piece of paper, write down: a) date, b) day of the week, c) time that you woke up, and d) time that you went to bed.
  2. Below that, record each yawn throughout the day and write down what time the yawns occurred according to your clock or watch. Keep your paper in a handy place so you are able to record each yawn.
  3. Repeat steps 1-2 for 7 days.
  4. At the conclusion of the 7 days, compare the amount of your yawns per day and also what times they occurred throughout the week.


  • Were there days when you yawned more than others?
  • If so, did you wake up or go to bed at different times than usual?
  • Did you tend to yawn more soon after waking up and/or just before bedtime?

Another quick experiment involves observing if yawns are contagious. The next time you are with a group of people, take a big yawn (make sure to cover your mouth out of courtesy to others). Did you notice whether anyone else yawned?