Prognosis

Heart Failure. Studies suggest that 11 - 37% of patients with heart failure also have sleep apnea. Central sleep apnea is particularly linked with heart failure. The evidence for the association between heart failure and sleep apnea includes:

• High blood pressure, which is associated with sleep apnea, is a major cause of later heart failure.
• Sleep apnea reduces oxygen levels and causes abnormal changes in blood pressure and heart rate that add to the burden of the failing heart.
• Obstructive sleep apnea can affect breathing functions that are particularly harmful for patients with existing congestive heart failure.
• Sleep apnea is associated with poorer survival in patients with heart failure. Some studies have suggested that treating sleep apnea with CPAP may improve heart function in these patients. However, a 2005 New England Journal of Medicine study found that CPAP did not improve survival in patients with heart failure and central sleep apnea

Atrial Fibrillation. Sleep apnea is more common in people with atrial fibrillation (irregular heartbeat) than in patients with other heart conditions. In a 2005 study published in Circulation, 49% of patients with atrial fibrillation were at risk for developing apnea, compared with 32% of general cardiology patients. An earlier study indicated that patients with untreated obstructive sleep apnea may be at increased risk for recurrence of atrial fibrillation. Patients with atrial fibrillation who received CPAP treatment had a lower risk for recurrence.

Metabolic Syndrome. The metabolic syndrome (also called Syndrome X) is a cluster of abnormalities that cause insulin resistance. Some of these factors, including hypertension and obesity, are also associated with sleep apnea. A 2004 study found that metabolic syndrome was nine times more common among patients with obstructive sleep apnea, independent of obesity.

Sleep Apnea as a Cause of Obesity

When it comes to sleep apnea and obesity, it is not always clear which condition is responsible for the other. For example, obesity is often a risk factor and possibly a cause of sleep apnea, but it is also likely that sleep apnea increases the risk for weight gain. Some studies indicate that sleep apnea disrupts rapid eye movement (REM) sleep, which, in turn, increases the risk for obesity. Research indicates that animals deprived of REM sleep tend to eat more. People with apnea may also become too tired to exercise and so put on weight.

Other Adverse Effects on Health

Sleep apnea is associated with a higher incidence of many medical conditions, other than heart and circulation. The links between apneas and the conditions are unclear.

• Pulmonary hypertension.
• Asthma. Sleep apnea may worsen asthma symptoms and interfere with the effectiveness of asthma medications. Treating the apnea may help asthma control.
• Diabetes.
• Kidney failure.
• Peripheral nerve damage (tingling, pain, or numbness in the hands and feet).
• Liver damage in obese individuals with sleep apnea. Recent research suggests that severe apnea may increase the risk of liver disease regardless of weight.
• Seizures, epilepsy, and other nerve disorders. Sleep apnea appears to pose a particularly risk for nocturnal epilepsy, a condition in which seizures occur during sleep.
• Headaches. Some studies strongly suggest that for some people sleep disorders, including apnea, may be the underlying causes of some chronic headaches. In some patients with both chronic headaches and apnea, treating the sleep disorder has been known to cure the headache, even the very severe and disabling form known as a cluster headache.
• Irregular menstrual periods. This occurs in about 40% of premenopausal women. It is not clear how they are related, but one study reported that treating apnea helped normalize periods.
• High-risk pregnancies. Some evidence suggests that there are higher rates of pregnancy complications in women with sleep apnea.
• Eye disorders, including glaucoma, conjunctivitis, dry eye, and various other infections and irritations. Findings presented at the 2003 annual meeting of the American Academy of Ophthalmology suggested that patients with sleep apnea may be at increased risk for glaucoma and should be tested for this eye disease. A vision-damaging condition called intracranial hypertension has also been observed some patients with sleep apnea.