Prognosis:

Sleep apnea has a strong association with several diseases, particularly those related to the heart and circulation.

Adverse Effects of Sleep Apnea on Heart and Circulation

A number of cardiovascular diseases -- including high blood pressure, heart failure, stroke, metabolic syndrome, and heart arrhythmias -- have an association with obstructive sleep apnea. This link may be because both cardiovascular illnesses and sleep apnea are associated with obesity and its consequences. However, large cohort observational studies have suggested that OSA itself may lead to incident cardiovascular disease. At this time, however, evidence of a clear causal relationship with any of these health problems is still weak. Some studies have found no significant independent risk for heart disease from obstructive sleep apnea. Likewise, whether treating obstructive sleep apnea decreases the incidence of any of these disorders remains to be proven.

High Blood Pressure. A number of studies have found a strong association between sleep apnea and high blood pressure (hypertension) even when obesity is not a factor. A weak, but still higher-than-normal, association with high blood pressure has also been observed in those who snore, wake frequently during the night, or have mild sleep apnea.

Coronary Artery Disease and Heart Attack. Sleep apnea has been associated with heart disease regardless of the presence of high blood pressure or other heart risk factors. Studies have shown that patients with moderate-to-severe obstructive sleep apnea have a higher risk for a heart attack.

Stroke. There is some association between the presence of sleep apnea and risk of death in patients who have previously had a stroke.

Heart Failure. Up to a third of patients with heart failure also have sleep apnea. Both central and obstructive sleep apnea are linked with heart failure. Obstructive sleep apnea can make heart failure worse, and patients with apnea have a higher mortality rate than those who do not. Treatment of obstructive sleep apnea may help improve heart function, although this is not certain.

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 high blood pressure and obesity, are also associated with sleep apnea. Metabolic syndrome seems to be more common among patients with obstructive sleep apnea, possibly regardless of obesity.

Diabetes. Severe obstructive sleep apnea is associated with increased risk for developing type 2 diabetes.

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.

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.
• 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. 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 cured the headache, even the very severe and disabling form known as a cluster headache.
• High-risk pregnancies. Sleep apnea causes higher rates of pregnancy complications, including gestational diabetes and high blood pressure.
• Eye disorders, including glaucoma, floppy eyelid syndrome, optic neuropathy conjunctivitis, dry eye, and various other infections and irritations. Some of these latter symptoms may be associated with CPAP treatment.

Psychological Effects

Studies report an association between severe apnea and psychological problems. The risk for depression rises with increasing severity of sleep apnea. Sleep-related breathing disorders can also worsen nightmares and post-traumatic stress disorder. Certainly, daytime sleepiness interferes with mental alertness and quality of life.

Effects on Bed Partners

Because sleep apnea so often includes noisy snoring, the condition can also adversely affect the sleep quality of a patient's bed partner. Spouses or partners may also suffer from sleeplessness and fatigue. In some cases, the snoring can disrupt relationships. Diagnosis and treatment of sleep apnea in the patient can help eliminate these problems.

Effects in Infants and Children

Failure to Thrive. Small children with undiagnosed sleep apnea may "fail to thrive," that is, they do not gain weight or grow at a normal rate and they have low levels of growth hormone. In severe cases, this may affect the heart and central nervous system.

Attention Deficits and Hyperactivity. Problems in attention and hyperactivity are common in children with sleep apnea. There is some evidence that such children may be misdiagnosed with attention-deficit hyperactivity disorder. Snoring, rather than sleepiness, is a stronger risk factor for hyperactivity in many of these children, especially boys under 8 years old. (Even children who snore and do not have sleep apnea may be at higher risk for poor concentration.)

Sleep Apnea and Automobile Accidents

Some researchers believe that sleepiness associated with sleep apnea is the greatest risk factor for car accidents. As many as 200,000 automobile accidents in the U.S. and 1,500 deaths from such accidents are caused by sleepiness. Studies continue to report that drowsy driving is as risky as drunk driving. Several studies have suggested that people with sleep apnea have two to three times as many car accidents, and five to seven times the risk for multiple accidents.