Sleep apnea is a condition characterized by episodes of stopped breathing during sleep. In normal conditions, the muscles of the upper part of the throat keep this passage open to allow air to flow into the lungs. These muscles usually relax during sleep, but the passage remains open enough to permit the flow of air.

Some individuals have a narrower passage and during sleep, relaxation of these muscles causes the passage to close and air cannot get into the lungs. Loud snoring and labored breathing occur. When complete blockage of the airway occurs, air cannot reach the lungs.

In deep sleep, patients with sleep apnea can stop breathing for a period of time (often more than 10 seconds). These periods of lack of breathing, called apneas, are followed by sudden attempts to breathe. These attempts are accompanied by a change to a lighter stage of sleep.

The result is fragmented sleep that is not restful, leading to excessive daytime drowsiness. Many patients are not aware of these “apneic” episodes, but bed partners can become concerned. The bed partner’s concern is often why a patient will come to see the doctor.

The classic picture of obstructive sleep apnea includes episodes of heavy snoring that begin soon after falling asleep. The snoring proceeds at a regular pace for a period of time, often becoming louder, but is then interrupted by a long silent period during which no breathing is taking place (apnea).

The apnea is then interrupted by a loud snort and gasp and the snoring returns to its regular pace. This behavior recurs frequently throughout the night. During the apneas, the oxygen level in the blood falls. Persistent low levels of oxygen called hypoxia may cause many of the daytime symptoms.

If the condition is severe enough, pulmonary hypertension may develop, leading to right-sided heart failure (or cor pulmonale). Sleep apnea occurs in all age groups and both sexes but is more common in men. Older obese men seem to be at higher risk, though as many as 40 percent of people with obstructive sleep apnea are not obese.

It has been estimated that as many as 18 million Americans have sleep apnea. Four percent of middle-aged men and 2 percent of middle-aged women have sleep apnea along with excessive daytime sleepiness.

Nasal obstruction, a large tongue, a narrow airway, and certain shapes of the palate and jaw seem to increase the risk. A large neck or collar size is strongly associated with obstructive sleep apnea. Ingestion of alcohol or sedatives before sleep may predispose a person to episodes of apnea.

Causes of Sleep Apnea

Certain mechanical and structural problems in the airway cause the interruptions in breathing during sleep. In some people, apnea occurs when the throat muscles and tongue relax during sleep and partially block the opening of the airway.

When the muscles of the soft palate at the base of the tongue and the uvula (the small fleshy tissue hanging from the center of the back of the throat) relax and sag, the airway becomes blocked, making breathing labored and noisy and even stopping it altogether.

Sleep apnea also can occur in obese people when an excess amount of tissue in the airway causes it to be narrowed. With a narrowed airway, the person continues their 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.

Researchers say congestive heart failure affects nearly 5 million people in the United States, and as many as a third to a half of all heart failure patients also suffer from obstructive sleep apnea. The sleep disorder causes sufferers to stop breathing periodically during sleep, which puts extra strain on the heart and can prompt potentially dangerous surges in blood pressure and heart rates.

Studies on experimental animals have shown that, in the absence of any other variable, obstructive sleep apnea results in left ventricular systolic and diastolic dysfunction. Sleep apnea has been associated with poorer survival in patients with congestive heart failure.

Targeting a common sleep disorder with treatment not only helps people with heart failure sleep better, it can make their hearts healthier. The Canadian Positive Airway Pressure study, called CANPAP, published in 2005, shows that people who suffer from both congestive heart failure and obstructive sleep apnea can benefit from a nighttime therapy known as continuous positive airway pressure (CPAP).

A masklike device worn over the nose at night that provides CPAP is an effective treatment for sleep apnea. Studies have shown that when CPAP is used on patients with sleep apnea and heart failure, they may experience not only improvements in episodes of sleep apnea.

But also a decrease in blood pressure and irregular heart rhythms as well as an improved ejection fraction. Some experts also suggest oxygen therapy or the asthma drug theophylline for this condition.

Because obstructive sleep apnea is so prevalent among people with congestive heart failure, researchers say the use of CPAP could be an important addition to conventional drug-based therapy for congestive heart failure. There needs to be a greater awareness among doctors about the role obstructive sleep apnea plays in congestive heart failure.

If you, or your bed partner, are aware of symptoms of heavy snoring, periods of not breathing, or awakening frequently in the night with a choking sensation, you should discuss these episodes with your physician and explore the possibility of sleep apnea. If CPAP isn’t effective or isn’t tolerated by the patient, surgery can be performed on the mouth and throat to open the air passages and decrease or eliminate episodes of apnea.