Sleep apnea is characterized by repeated episodes of breathing cessation (apnea) during sleep. These episodes last from 10 seconds to nearly a minute, ending with a brief partial arousal. This can occur (and disrupt sleep) hundreds of times each night. An estimated 18 million American adults have obstructive sleep apnea, according to the National Sleep Foundation, most of them undiagnosed.
The most pervasive and troublesome symptom of sleep apnea is excessive daytime sleepiness caused by poor sleep at night. People who have sleep apnea may fall asleep during the day while reading or even while driving, so there is a major risk of motor vehicle accidents. They may also suffer from memory loss and personality changes. Although loud snoring is a common sign of sleep apnea, snoring itself does not indicate obstructive sleep apnea.
More than half of individuals with sleep apnea also have high blood pressure, and their blood pressure does not fall during sleep as it does in most people. In fact, sleep apnea has been shown to be an independent, treatable cause of high blood pressure. Research suggests that sleep apnea also doubles the risk of stroke in some people.
Other medical problems have also been linked to sleep apnea. For example, patients who have an underlying irregular heart rhythm known as atrial fibrillation are less likely to have adequate control of this disease if sleep apnea is also present and untreated. Some evidence suggests that periods of apnea and the resulting low levels of oxygen in the blood, along with persistently high blood pressure, increase the risk of coronary heart disease and blood glucose intolerance.
Obtaining a sleep history is key to recognizing sleep apnea. Input from a bed partner can be especially important because the partner is likely to notice signs associated with frequent periods of apnea, such as snoring or gasping for breath.
Definitive diagnosis typically requires spending one night in a hospital sleep laboratory to undergo polysomnography, a set of sleep studies that monitor brain waves (to determine which stages of sleep are associated with episodes of apnea), heart rhythms, airflow and breathing patterns, eye and leg movements, and blood oxygen levels.
Some people are able to undergo monitoring at home using portable equipment, but the results must still be interpreted by a sleep specialist. Recent research has suggested that home studies can be as effective as laboratory-based testing for people with clear symptoms of moderate to severe sleep apnea and no significant health issues (such as severe lung disease or heart failure) that could affect the results. If the test is negative but your symptoms persist, you will need full testing at a sleep clinic. A sleep specialist can perform an evaluation to determine if you’re a candidate for either type of sleep testing.