What are the risk factors for sleep apnea?

Gender. More men than women appear to have sleep apnea. Sleep apnea may be under-diagnosed in women. In general, older women have the same incidence as men their own age. A range of studies has reported apnea or hypopnea in between 9% and 24% of men and 4% to 15% of women.

Age. Sleep apnea affects people of all ages. Although it is most common in older adults, it has been reported in between 1.6% to 3.4% of children. Some experts believe that sleep disorder breathing may occur in as many as 11% of children. Interestingly, one study suggested that although prevalence of sleep apnea increases with age, its health consequences decline. In the study, apnea posed more of a threat to a person's health before age 45 than afterward.

Ethnicity. African Americans face a higher risk for sleep apnea than any other ethnic group in the United States.

Geography. According to one study, although urban dwellers are more likely to report disturbed sleep, particularly as a result of stress, rural dwellers have a significantly higher risk for apnea.

Obesity. Obesity, particularly having fat around the abdomen (the so-called apple shape), is a particular risk factor for sleep apnea, even in adolescents and children. (It should be noted, however, that many people with sleep-disordered breathing, particularly women and small children, are not obese.)

Immune abnormalities. High levels of certain immune factors are present in people with sleep apnea, including tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6). Elevated levels of TNF-alpha can cause fatigue, shortness of breath, and weakness in the heart's pumping action. IL-6 and TNF-alpha may both play a role in obesity as well.

Body position. Body position greatly affects the number and severity of episodes of obstructive sleep apnea, with at least twice as many apneas occurring when a person lies face upward than when the person lies on his or her side. This may be due to the effects of gravity, which cause the throat to narrow when a person lies on the back.

Other medical conditions. Individuals with severe heartburn (Gastroesophageal reflux disease, or GERD) appear to be at higher risk for sleep apnea. Sleep apnea is also associated with higher rates of heart failure.

Smoking. Smokers are at higher risk for apnea, with heavy smokers (more than 2 packs a day) having a risk 40 times greater than nonsmokers.

Alcohol. Alcohol use has been associated with apnea, although studies are mixed.

Family history . Family history of OSA, although no genetic pattern has been proven

Obesity or excessive weight gain is a primary risk factor. Additional tissue in the throat narrows the airway, which is then more easily blocked when the muscles are relaxed. Age and gender are also significant factors in sleep apnea. Aging is usually accompanied by a loss of muscle mass and if the muscles near the airways are more lax, it is easier for them to become blocked. Men seem more likely to experience sleep apnea, although it may be underdiagnosed in women.

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