Library · Physiology
Why you yawn
Make it clearer
Yawning is opening your mouth wide without meaning to, with a long deep breath in followed by a slow breath out. It lasts, on average, about five seconds.
The honest thing is to say what is still unknown: science is still looking for a full explanation of the mechanism and the purpose of yawning, and the debate over what it is good for is still open. There is no settled answer, and anyone who hands you one anyway is getting ahead of the evidence.
What has been described is when it shows up. The evidence suggests that the most common trigger is sleepiness, that drowsy feeling, and several studies using physiological measures describe alertness rising after a yawn.
And then there is the strangest part: it is contagious. Just seeing someone yawn, hearing it, reading about yawning or even thinking about it is enough to make you want to. It has probably happened to you while reading this.
In brief
A yawn is an involuntary, wide opening of the mouth with a long deep inhalation and a slow exhalation; it averages about five seconds.
Science is still looking for a full explanation of its mechanism and its purpose, and the debate over its usefulness remains open.
The evidence suggests that the most common trigger is sleepiness, and several studies describe a rise in alertness after yawning.
It is also contagious: seeing it, hearing it, reading about it or even thinking about it is enough to set it off.
Sources (1)
- International Journal of Applied and Basic Medical Research (PubMed Central, U.S. National Library of Medicine)Yawning and its physiological significancePublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated