Sleep apnea – literally, without breath – is as common as adult diabetes, affecting more than 12 million Americans, according to the National Institutes of Health. It happens during sleep, when breathing pauses or becomes shallow. Apnea is a serious disorder that can have significant consequences, largely because it so often goes undiagnosed. The patient may not realize they have it; they may report only being unusually tired during the day, or having irregular heartbeats.

The three types of apnea are:

Obstructive sleep apnea: occurs when the airway is blocked or has collapsed. Loud snoring can result as air squeezes past the blockage. Most sleep apnea patients are overweight, but the thin can also be affected.

Central sleep apnea is not as common as the obstructive type. In central sleep apnea, the breathing muscles do not receive the correct signals from the brain. No effort to breathe is made during pauses. Typically, loud snoring isn’t present in central sleep apnea.

Complex sleep apnea is a combination of the other two types.

If untreated, sleep apnea can:

• Increase the risk for heart failure, or worsen it.

• Increase the risk for obesity, diabetes, high blood pressure, stroke, and heart attack.

• Increase the risk of accidents, both work related or driving.

The most common signs of sleep apnea are:

• Loud snoring

• Bed partner reports episodes of pauses in breathing

• Daytime drowsiness

• Abrupt awakenings with shortness of breath

• Morning headache

• Dry mouth or sore throat upon awakening

• Insomnia

In obstructive sleep apnea, the muscles in the back of the throat relax. The soft palate – the triangular piece of tissue in the back of the throat, the tonsils and the tongue are all supported by these muscles. Upon relaxation, the airway narrows or closes as you breathe in, temporarily stopping the breathing. The amount of oxygen in your blood lowers, and sensing this, the brain awakens you so that the airway can be reopened, often causing a gasping or snorting sound. You may not remember being awake as the pauses are brief. However, if they happen often enough they may disrupt your ability to reach REM sleep, making you feel tired and drowsy the next day.

Heart disease is the most common cause of central sleep apnea; less commonly, stroke may cause it. If you have central sleep apnea you are more likely to remember being awake during the night.

In cases of complex sleep apnea, patients have upper airway obstruction, but they may also report lapses of breathing effort, and poor breathing rhythm.

Factors that put you at risk for obstructive sleep apnea are:

• Neck size: the circumference of your neck may indicate risk of sleep apnea. A thick neck may narrow the airway. This condition may be genetic.

• High blood pressure is common with sleep apnea.

• Overweight: Your breathing may be obstructed by fat deposits around the upper airway.

• Gender: Males are twice as likely as women to suffer from sleep apnea. But if women are overweight, the risk increases. It also increases after menopause.

• Being elderly: Adults older than 65 are two to three times more likely to suffer sleep apnea.

• Substances: Use of sedatives, tranquilizers or alcohol relaxes the throat muscles.

• Smoking: obstructive sleep apnea is found three times more often in smokers. The amount of inflammation and fluid retention in the upper airway may increase with smoking.

• Heart disorders: If you have congestive heart failure or atrial fibrillation, you are more likely to develop central sleep apnea. The cardiovascular system can be strained by sleep pauses: your risk for high blood pressure increases up to 2-3 times. An underlying heart disease can be worsened by pauses in breathing, and the combination can even lead to sudden death from heart failure. Complex sleep apnea seems to be more common in heart patients. Central sleep apnea is commonly a result, rather than a cause, of heart problems.

• Stroke or brain tumor can adversely affect the brain’s ability to regulate breathing.

• Family history: You are more at risk for sleep apnea if others in your family have or have had it.

• Fatigue: Restorative sleep is made impossible by breathing pauses. Patients may experience fatigue, extreme drowsiness during the day, and irritability, and may feel moody or depressed; you may find yourself falling asleep at work or while driving, and you may be unable to concentrate well.

• Problems at school or with general behavior problems in children and teens may be caused by sleep apnea.

• Medical procedures and medications: Certain medications may cause obstructive sleep apnea, and because those who take them tend to have breathing problems in the first place, they may be at increased risk for complications following surgery. In this situation, undiagnosed sleep apnea is especially risky.

• Partners: If your partner has sleep apnea, you may well be significantly affected. Loud snoring may disrupt your own sleep; you may find it necessary to go to another room, or perhaps sleep on the floor.

• Other conditions: memory problems, mood swings, depression, getting up at night to urinate, morning headaches, gastric reflux, and impotence may be more common in people with sleep apnea. Children and adults may be diagnosed with attention deficit disorder (ADD), with or without hyperactivity.

A few tests may help to diagnose sleep apnea:

Nocturnal polysomnography: monitors heart, brain, and lung activity, arm and leg movements, breathing patterns and blood oxygen levels during sleep.

Oximetry: measures the oxygen level in the blood, which drops during pauses, and rises with awakenings. Because this test does not detect all sleep apneas, your doctor may recommend polysomnography to confirm the diagnosis.

Portable cardiorespiratory: may be recommended under certain circumstances; involves simple tests performed at home, to measure oxygen levels and airflow, and reveal breathing patterns.

In cases of obstructive sleep apnea, you may be referred to an ear, nose, and throat doctor to determine if there are blockages in your nose or throat. To determine the cause of central sleep apnea, you may be referred to a cardiologist, or a neurologist. Your doctor may also recommend you lose weight or stop smoking. If these measures do not help, devices to keep your airway clear while you sleep are available. Extreme cases may require surgery to remove any excess tissue in your nose and/or throat, or to enlarge or clear the airway. Nasal surgery will remove polyps if they exist, or what is called a “deviated nasal septum” (a crooked partition between the nostrils), or remove enlarged adenoids and/or tonsils.

For treatment of central or complex sleep apnea, treatment for any underlying heart or neuromuscular disorders will be recommended. Supplemental oxygen may help in cases of central sleep apnea. Again, various devices are available to deliver oxygen to the lungs.

To help yourself get better sleep, lose weight if you are overweight, avoid alcohol and medications like sleeping pills or tranquilizers, sleep on your stomach or on your side, not on your back. Sleeping on the back can be prevented by attaching an object such as a tennis ball to your pajama top. Use a saline nasal spray at night to keep the nasal passages open.