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Many agree that yawning is a reflexive deep inhalation caused by decreased oxygen levels in the blood, and is most often associated with sleepiness or boredom. Excessive yawning (1-4 yawns per minute) is associated with a variety of conditions.
There are two things that happen when we yawn, those being that we open our jaw wide and we take a very deep breath. This only happens for a moment and creates a tremendous pressure in the lungs. Although some scientists offer the low oxygen hypothesis, others believe yawning may be: - A social communication signal (this is backed up by the fact that yawning appears to be "contagious"!)
- A way of regulating activity or arousal levels
- A protective reflex which maintains proper lung inflation and prevents collapsed alevoli.
These possibilities overlap in large part, but none appear to have been unequivocally proven. Whatever the physiology behind yawning, it is clear that it is a basic motor behavior; yawning can remain intact in an otherwise paralyzed person, and yawning has been reported in fetuses.
Causes & Development
The majority of disorders associated with yawning are those of the central nervous system, including epilepsy, encephalitis, brain tumors, multiple sclerosis and progressive supranuclear palsy. Excessive yawning is also associated with opiate withdrawal and the consumption of a variety of drugs that affect neurotransmitters, such as drugs prescribed for Parkinson's disease or depression. Studies have shown that people with brain lesions, tumors and certain kinds of epilepsy often yawn excessively, while schizophrenics yawn very little.
Yawning can also be the first sign of what is called the vasovagal reaction. Potentially adversive stimuli, such as needle pricks or even generalized anxiety about some future event, can lead to increased activity in the vagus nerve. In some people the increased activity can cause their blood pressure and heart rate to fall. If the reaction is mild, these people may yawn, or feel apprehensive or restless. In more severe cases a person can exhibit dizziness, nausea, palpitation or even fall into unconsciousness.
Seek medical attention if
If the symptom concerns you, you should consult your doctor.
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Conditions that suggest Excessive Yawning:
Risk factors for Excessive Yawning:
KEY | | Weak or unproven link |  | | Proven definite or direct link |
GLOSSARY
Anxiety
Apprehension of danger, or dread, accompanied by nervous restlessness, tension, increased heart rate, and shortness of breath unrelated to a clearly identifiable stimulus.
Central Nervous System (CNS)
A collective term for the brain, spinal cord, their nerves, and the sensory end organs. More broadly, this can even include the
neurotransmitting hormones instigated by the CNS that control the chemical nervous system, the endocrine glands.
Epilepsy
Chronic brain disorder associated with some seizures and, typically, alteration of consciousness.
Lesion (Lesions)
Any damage to tissue structure or function; an abnormal change in body tissue caused by disease or injury. A scar is a lesion, as is cancer, a stomach ulcer or a pimple.
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
Multiple Sclerosis (MS)
Demyelinating disorder of the central nervous system, causing patches of sclerosis (plaques) in the brain and spinal cord, manifested by loss of normal neurological functions, e.g. muscle weakness, loss of vision, and mood alterations.
Nausea
Symptoms resulting from an inclination to vomit.
Neurotransmitters (Neurotransmitter)
Chemicals in the brain that aid in the transmission of nerve impulses. Various Neurotransmitters are responsible for different functions including controlling mood and muscle movement and inhibiting or causing the sensation of pain.
Parkinson's Disease (Parkinson's)
A chronic, slowly-progressing disease of the nervous system characterized clinically by the combination of tremor, rigidity, extreme slowness of movement, and stooped posture. It is characterized pathologically by loss of dopamine in the substantia nigra.
Vagus Nerve
Also called the pneumogastric nerve, this is the tenth cranial nerve, with many fibers leading to parasympathetic ganglia in internal organs, and can be considered the presynapse starter for the upper parts of the parasympathetic functions.
Last updated: Apr 13, 2008
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