Risk Factors

Gender. More men than women appear to have sleep apnea. In the U.S., about 4% of men and 2% of women between the ages of 30 - 60 meet the criteria for obstructive sleep apnea. Such people have at lease five episodes of apnea or hypopnea (shallow nighttime breathing) for each hour of sleep plus excessive daytime sleepiness. A much higher percentage has just one of these two conditions.

Sleep apnea actually may be underdiagnosed in women, particularly 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 equalizes 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 fully explain 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, including a small percentage of children.

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.

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. However, 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, 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:

  • 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. Some people have specific abnormalities in the soft area (palate) at the back of the mouth and throat that may lead to sleep apnea. These abnormalities include:

  • The soft palate is stiffer, larger than normal, or both. An enlarged soft palate 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. Those who smoke more than two packs a day have a risk 40 times greater than nonsmokers.

Alcohol. Alcohol use has been associated with apnea, although studies are mixed. A major survey reported that 53% of people who use alcohol to help fall 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). GERD is a condition caused by acid backing up into the esophagus. It is a common cause of heartburn. GERD and sleep apnea often coincide. In one study, almost half of apnea patients had symptoms of GERD. Some experts suggest that the backup 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 suggests that treating sleep apnea with continuous positive airway pressure (CPAP) may reduce GERD symptoms by nearly 50%. However, obesity is common in both conditions and may be the common factor. More research is needed to clarify the association.

Polycystic Ovary Syndrome (PCOS). In a 2000 study, women with PCOS were 30 times more likely than other premenopausal women to have obstructive sleep apnea and excessive daytime sleepiness. Women with PCOS produce high amounts of male hormones, particularly testosterone, which 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.

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.