Why people take yawn ?
A yawn (from the Middle English yanen, an alteration of yonen or yenen, which in turn comes from the Old English geonian), is a reflex of simultaneous inhalation of air and stretching of the eardrums, followed by exhalation of breath. Pandiculation is the term for the act of stretching and yawning simultaneously. Yawning is associated with tiredness, stress, overwork, lack of stimulation, or boredom. Yawning can also be a powerful non-verbal message with several possible meanings, depending on the circumstances. In humans, yawning has the infectious quality, i.e. seeing a person yawning, or just thinking of yawning, can trigger yawning which is a typical example of positive feedback. The exact causes of yawning are still undetermined. The claim that yawning is caused by lack of oxygen has not been substantiated scientifically. Some claim that yawning is not caused by lack of oxygen, for the reason that yawning allegedly reduces oxygen intake compared to normal respiration. Another spec
