Sleep Apnea

Description

Risk Factors

Gender. More men than women appear to have sleep apnea. In the US, about 4% of men and 2% of women between the ages of 30 to 60 years meet the criteria for obstructive sleep apnea. In other words, such people have at lease five episodes of apnea or hypopnea (shallow nighttime breathing) each hour of sleep plus excessive daytime sleepiness. A much higher percentage has just one of these two conditions. About 16% of men and 22% of women are sleepy during the day, and 24% of men and 9% of women experience more than five apneas or hypopneas per hour a night. Most people with sleep apnea are not aware that they have it.

Sleep apnea actually may be under-diagnosed in women, particularly in older women. In general, older women have the same incidence of sleep apnea as men their own age. It is not clear why apnea occurs more often in men than women before menopause and why prevalence equalized after menopause. Men tend to have larger necks and to weigh more than women and women tend to gain weight and develop larger necks after menopause. However, studies have not found that these physical factors explained the differences in risk by gender in young adults or the increase in sleep apnea in postmenopausal women.

Age. Sleep apnea is most common and its symptoms are worse in middle-aged adults (between 40 and 60 years old). Nevertheless, it affects people of all ages, and, in fact, has been reported in between 1.6% to 3.4% of children.

Interestingly, one study suggested that although the 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. Other groups at increased risk include Pacific Islanders and Mexicans.

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.

Being Obese

Obesity, especially 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-related breathing disorders, particularly women and small children, are not obese. Also, not all people who are obese have sleep apnea. Specific anatomical and physiological properties in the airways are more likely to be present in obese individuals with apnea.

Physical Characteristics

Having a Larger Neck. Having a large neck is a risk factor for sleep apnea. In fact, the larger necks in men may be the primary reason for their higher risk for sleep apnea compared to women. A neck measurement of 17 inches or greater in men or at least 16 inches in women is one indicator that may suggest the condition. Postmenopausal women are more likely than younger women to have sleep apnea, in part because they tend to be heavier and have larger necks.

Specific Facial and Skull Characteristics. Structural abnormalities in the face and skull may be responsible for many cases of sleep apnea. These are likely to be the cause in many non-obese people with early-onset sleep apnea, particularly if they also have a family history of the problem.

Specific physical characteristics that may increase the risk for sleep apnea in both adults and children include the following:

• A long lower part of the face.
• Brachycephaly (a birth defect in which the head tends to be shorter and wider than average).
• A narrow upper jaw.
• A receding chin.
• An overbite.
• A larger tongue.

Characteristics in the Soft Palate Throat. Some people have specific abnormalities in the soft palate (the soft area at the back of the mouth) and throat that may prove to cause sleep apnea:

• The soft palate is stiffer, larger than normal, or both. An enlarged soft palate, in fact, may be a significant risk factor for sleep apnea.
• The soft palate and the walls of the throat around it collapse easily.

Smoking and Alcohol Use

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

Alcohol. Alcohol use has been associated with apnea, although studies are mixed. A major 1999 survey reported that 53% of people who use alcohol to sleep experience symptoms of sleep apnea. Another study found no relationship.

Medical Conditions Related to Sleep Apnea

Diabetes. Diabetes is associated with sleep apnea and snoring. It is not clear if there is an independent relationship between the two conditions or whether obesity is the only common factor.

Gastroesophageal Reflux Disease (GERD). Gastroesophageal reflux disease (GERD) is a condition caused by acid backing up into the esophagus and is a common cause of heartburn. GERD and sleep apnea often coincide. In one study, almost half of apnea patients had symptoms of GERD, and these symptoms also tend to be worse at night and in the morning and particularly hard to treat. Some experts suggest that the back of up of stomach acid in GERD may produce spasms in the vocal cords (larynx), thereby blocking the flow of air to the lungs and causing apnea. Or, apnea itself may cause pressure changes that trigger GERD. Some evidence, in fact, suggests that treating sleep apnea with continuous positive airway pressure (CPAP) may reduce GERD symptoms by nearly 50%. It should be noted, however, that obesity is frequent in both conditions and may be the common factor. More research is needed to clarify the association.

Polycystic Ovary Syndrome (PCOS). In one 2000 study, women with polycystic ovary syndrome (PCOS) were 30 times more likely than other premenopausal women to have obstructive sleep apnea and excessive daytime sleepiness. In PCOS women produce high amounts of androgens (male hormones), particularly testosterone. The elevated levels of male hormones can cause obesity, facial hair, and acne. About half of PCOS patients also have diabetes. Obesity and diabetes are both associated with sleep apnea and may be the common factors.

Chronic Problems in the Upper Airways. A 2001 Swedish study found that people with respiratory tract disorders, including asthma, chronic bronchitis, or seasonal allergies, reported symptoms of sleep apnea more often than those without any of these ailments. Not all research supports the association, however, and more studies are needed.

Hypothyroidism. In rare cases, hypothyroidism has been reported as possible cause of sleep apnea. In such cases, treating the thyroid condition improves the sleep apnea.

Glaucoma. Preliminary findings presented at the 2003 annual meeting of the American Academy of Ophthalmology suggest that patients with sleep apnea may be at increased risk for glaucoma and should be tested for this eye disease.