About Sleep Apnea

Obstructive sleep apnea is a serious medical condition in which the soft tissues at the back of the throat completely close off the airway so that air cannot flow into the lungs. This airway blockage can reduce the amount of oxygen reaching the brain and body. The brain is very sensitive to drops in blood oxygen. When the oxygen level drops, the brain alerts the muscles in the airway to tighten up and unblock the air passage. As the air starts to flow into the lungs again, a loud gasp or snort (sometimes called a 'resuscitative snort') is heard. The patient may also sit up or move violently before falling back into a light sleep. Bruxism or Teeth Grinding is also a compensatory mechanism which the body uses to try to keep the airway open. This excessive grinding can cause temporomandibular joint disease.Then breathing (and frequently snoring) begins again. This process of blocking and unblocking the airway causes a significant and very negative disruption of sleep patterns.

When there is a cessation of air flow at the mouth and nose for more than 10 seconds an apnea episode has occurred. If a person experiences 30 or more apnea episodes during a seven hour sleep period they are considered to be suffering from sleep apnea and over time they experience the serious effects of not enough oxygen reaching their vital organs (heart, brain, etc).

Apnea severity is usually categorized by the frequency of apnea episodes:

mild 5 to 15 episodes per hour
moderate   15 to 30 episodes per hour
severe more than 30 episodes per hour

These episodes can last anywhere between 10 to 120 seconds each, terminating with at least a partial awakening. A severe apnea patient may have as many as 300 episodes per night!


A hypopnea occurs when there is a partial obstruction somewhere in the airway. It is severe enough to obstruct airflow resulting in a decrease of the oxygen levels in the blood greater than 4%. Hypopnea episodes can disrupt sleep patterns but do not generally awaken the patient, as sleep apnea does.

Diagram of normal air flowDiagram of air flow during sleep apnea