With a narrowed airway, the person continues his or her efforts to breathe, but air cannot easily flow into or out of the nose or mouth. Unknown to the person, this results in heavy snoring, periods of no breathing, and frequent arousals, causing abrupt changes from deep sleep to light sleep. Ingestion of alcohol and sleeping pills increases the frequency and duration of breathing pauses in people with sleep apnea. During the apneic event, the person is unable to breathe in oxygen and to exhale carbon dioxide, resulting in low levels of oxygen and increased levels of carbon dioxide in the blood. These changes, along with air pressure and muscle changes, lead to arousals from sleep.
Breathing is resumed, often with a loud snort or gasp.
Frequent arousals, although necessary for breathing to restart, prevent the patient from getting enough restorative and deep sleep. Because of the serious disturbances in their normal sleep patterns, people with sleep apnea often feel very sleepy during the day and their concentration and daytime performance suffer. The consequences of sleep apnea range from annoying to life-threatening. They include depression, irritability, sexual dysfunction, learning and memory difficulties, and falling asleep while at work, on the phone, or driving. It has been estimated that up to 50 percent of sleep apnea patients have high blood pressure.