The question that has often come to the mind of many a tired school child sitting in a humid classroom is why exactly do we yawn. Well, a research team at Stanford University School of Medicine, led by neuroscientist and psychiatrist Maurice Ohayon, recently discovered that there is a link between yawning and how much people sleep.
The team studied the sleeping habits of over 160,000 Americans for an average of 4 years each, and found that the more a person yawned, the more likely they were to sleep 12 minutes longer per night.
In addition, this group of people also slept an average of 45 extra minutes over a 24 hour period, leading scientists to believe that a long yawn could be a sign of drowsiness. And while they didn’t find exactly why yawning is linked to tiredness, they did find that people who yawned more often also had less insomnia.
This could be because sleep-deprived people are already tired, so they yawn more frequently in an effort to combat this exhaustion. It’s known that when the body is very sleepy, it releases certain chemicals like adenosine, which can trigger tiredness.
People who were sleep-deprived released 11% more yawning in a 24 hour period when compared to those who didn’t feel as sleepy throughout the day.
Furthermore, when people were exposed to bright light during mid-day, they yawned less frequently than usual. Light is a big factor when it comes to feeling alert or drowsy, so this discovery could link light exposure to the yawning-sleepiness relationship.
The study analyzed people of all ages, so there’s no way of knowing exactly how many yawns are too many for a certain age group. But based on what they found, Ohayon said that yawning should be used as an indicator for doctors to measure whether or not their patients are getting enough sleep.