A reflex of simultaneous inhalation of air and stretching of the eardrums, followed by exhalation of breath.
The act of yawning and stretching simultaneously is known as pandiculation.
Associated with tiredness, stress, overwork, lack of stimulation, and boredom.
Can also be a non-verbal message with several possible meanings.
Activated chemicals include serotonin, dopamine, glutamic acid, and nitric oxide increase frequency of yawning.
Increased brain opioid neurotransmitters such as endorphins reduce the frequency of yawning.
Opioid withdrawal associated with increased frequency of yawning.
Selective serotonin reuptake inhibitor use associated with yawning.
Has a contagious quality.
A human mirror neuron system exists that allows imitation of certain motor actions when we view others performing the same action: contagious yawning.
60-70% of people who find that seeing a person yawn in real life or a photo, even reading about it compels them to do the same thing.
Contrary to popular thought, yawning bears no relation to dipping energy levels.
Yawning’s contagiousness seems to indicate more about personality than sleepiness.
Yawning is a sign of empathy.
Catching yawns may be an unconscious sign of recognition of other people’s emotions: smile or frown at someone when they do the same to you.
Most children did not begin contagious yawning until they were around four years old, the age when empathy skills begin to develop.
Young people with autism, who may have trouble feeling empathy, were less likely to yawn contagiously than their peers without autism.
The severity of autistic symptoms were much less likely to yawn contagiously than those with milder symptoms.
People with certain psychopathic traits may be less likely to catch a yawn from others.
The less empathy a person had, the less likely they are to catch a yawn.
The younger you are, the more likely you are to catch yawns.
In a study of 328 people, 82% of people under 25 contagiously yawned, while just 60% of people ages 25 to 49 contagiously yawned, and only 41% of people over age 50 were contagious yawners.
This suggests people may generally become less susceptible to contagious yawning as they age, possibly because they pay less attention to the behavior in others.