With obstructive sleep apnea, the airway collapses and stopping the flow of air into the lungs while sleeping. When the oxygen level in the brain becomes low enough, the sleeper will awaken at least partially. Upon waking, the obstruction in the throat will be cleared and allow for proper air flow again. This occurrence is called an apnea, and it is usually accompanied by a loud gasp.
Those with obstructive sleep apnea (OSA) often have disrupted sleep and low blood oxygen levels. When left untreated, OSA has been associated with excessive daytime sleepiness and cardiovascular problems up to and including sudden death.
Upper airway resistance syndrome (UARS) is a condition that lies midway between benign snoring and true obstructive sleep apnea. While people with UARS suffer from many of the symptoms of OSA, a normal sleep test will typically be negative. There are several different treatments for sleep apnea, depending on the severity of the problem and the anatomic structures involved in the obstruction. Sometimes the cure can be as simple as wearing a dental appliance at night. In more complex cases, the cure may include corrective jaw surgery.