A yawn is a reflex of simultaneous inhalation of air and stretching of the eardrums, followed by exhalation of breath. Pandiculation is the act of yawning and stretching simultaneously.
Yawning is commonly associated with tiredness, stress, overwork, lack of stimulation and boredom. In humans, yawning is often triggered by others yawning (e.g. seeing a person yawning, talking to someone on the phone who is yawning or thinking of yawning) and is a typical example of positive feedback. This "infectious" yawning has also been observed in chimpanzees and dogs.
I am so tired.
If I'm yawning and my husband touches my lip with his finger - it makes the yawn stop. I hate it, but he thinks it's so funny!
It's only 8:30pm, but I am off to bed.
For more of the letter "Y", check out Jenny's blog and her Alphabe-Thursday.