Re: Is there a disease or illness that is characterized by constant yawning?

Vanessa,

According to conventional wisdom, yawning is a reflexive deep inhalation caused by decreased oxygen levels in the blood, and is generally associated with sleepiness or boredom. My review of the Medline literature suggests that the only thing known for certain about yawning is that nearly all vertebrates do it. Some scientists still offer the low oxygen hypothesis, others say yawning is a social, communicatory signal, others argue that it is a way of regulating activity or arousal levels, and still others that yawning is a protective reflex which maintains proper lung inflation and prevents collapsed alevoli. These possibilities overlap in large part, but my admittedly cursory review did not convince me that any of them 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.

Excessive yawning (1-4 yawns/minute) is associated with a variety of conditions. The majority of these are disorders of the central nervous system, and include epilepsy, encephalitis, brain tumors, multiple sclerosis and progressive supranuclear palsy. Excessive yawning is also associated with opiate withdrawl and the consumption of a variety of drugs that affect neurotransmitters, such as drugs prescribed for Parkinson's disease or depression.

Yawning can also be the first manifestation of what is called the vasovagal reaction. Potentially adversive stimuli, such as needle sticks 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.

As you can see, excessive yawning can have a variety of underlying causes. If the symptom concerns you, you should consult your doctor.

Mosbey Consumer Health is a company that runs a medical encyclopedia on the net. It has information concerning a variety of health issues, including symptoms of illnesses. I can't vouch for the accuracy of the other entries or the company itself, but its information on yawning is in line with what I've read.

The information provided is a summary of the medical literature on the symptomatology of excessive yawning as I understand it. However, I am not a medical doctor, and this article should not be considered medical advice or used for self treatment.

If you have any questions or comments, or would like a list of some of the references I used to construct this answer, please send me an email.