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Excessive yawning
Yawning involves opening the mouth involuntarily while taking a long, deep breath of air. This is usually done as a result of drowsiness or weariness. Excessive yawning is yawning that happens more often than would be expected, even if drowsiness or weariness is present.
Yawning is a normal response to fatigue and drowsiness, but excessive yawning can be caused by a vasovagal reaction. This reaction is caused by the action of a nerve, called the vagus nerve, on the blood vessels. It may indicate a heart problem.
Normal yawning may happen when someone else yawns.
Hermanowicz N. Cranial nerves IX (glossopharyngeal) and X (vagus). In: Goetz CG, ed. Textbook of Clinical Neurology. 3rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 13.
LeWinter MM. Pencardial diseases. In: Libby P, Bonow RO, Mann DL, Zipes DP, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 70.
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