by Howard Miller

Created on: May 15, 2007

Sleep Apnea

What you may well need to know

Sleep apnea is a far more common - and far more serious - disorder than most people realize. Its actual prevalence is not known with any accuracy because it is grossly under diagnosed. Therefore, we can only estimate from samples in the population. The most often given estimate is that approximately 18,000,000 people in the United States are afflicted with sleep apnea. Only about ten percent of this number is known and diagnosed.

So what is this virtually endemic disorder? Literally, apnea means "without breath," and this is exactly what it is describing. In sleep apnea, there are periods during which the afflicted individual stops breathing. Normally, during sleep, breathing is relatively smooth and continuous; there is little pause between the end of one breath and the beginning of the next, perhaps two or three seconds during slow, relaxed respiration, but rarely much more than that. Apnea is defined as a pause of ten seconds or more. A pause of ten seconds between breaths during sleep means that something is wrong.

In general terms, there are two sources of possible problems in breathing. One is when something is blocking the airway; the other is when the brain does not get the signal to breath to the muscles. The first, and more common type is called obstructive apnea; the second is called central apnea. Sometimes, these two combine in the same individual, a condition labeled, "mixed-complex."

Normally, during sleep, the muscles of the tissues that surround the airway relax, lose the tone that they have during wakefulness and the soft tissues surrounding the airway, which include the palate, tongue, epiglottis, tonsils, mucosal lining, and the blood vessels and fat deposits in the neck, can narrow the airway. This phenomenon causes snoring, but when the obstruction becomes complete, or nearly so, it blocks the airway to a degree that interferes with respiration - obstructive apnea.

In central apnea, there is a neurological impairment from disease, injury, or drugs that interferes with the mechanism that tells the brain that there is not enough oxygen and it needs to send a signal to the respiratory muscles to take a breath. Many common sedatives, including over the counter sleep aids and alcohol, can suppress the respiratory center to cause, or contribute to, apnea. In both etiologies, the apneic events cause hypoxia, or a lack of oxygen, which sets off a series of physiologic changes that result in partial awakening,

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