Understanding the Causes of Sleep Apnea, and Factors That Increase Your Risk

A blockage or narrowing of the airways in your nose, mouth, or throat generally causes obstructive sleep apnea (OSA). This usually occurs when the throat muscles and tongue relax during sleep and partially or completely block the airway. When you stop breathing or have reduced flow of air into your lungs during sleep, the amount of oxygen in your blood decreases briefly.

Obstructive sleep apnea can also occur if you have bone deformities or enlarged tissues in your nose, mouth, or throat. For example, you may have enlarged tonsils. During the day when you are awake and standing up, this may not cause problems. But when you lie down at night, the tonsils can press down on your airway, narrowing it and causing sleep apnea.

See pictures of normal and blocked airways during sleep.

Other factors that may contribute to sleep apnea include:

• Drinking alcohol, which affects the part of the brain that controls breathing. This may relax the breathing muscles and cause a narrowing of the airway and sleep apnea.
• Obesity. Fat in the neck area can press down on the tissues around the airways. This narrows the airways and can cause sleep apnea. About 70% of people who have sleep apnea are obese.¹
• Some medicines that are taken for conditions such as allergies, depression, insomnia, or anxiety. These medicines, especially sedatives, can also relax the muscles and tissues in the throat, causing it to narrow.

In children, the main cause of sleep apnea is large tonsils or adenoids .

Obstructive sleep apnea (OSA) causes you to stop breathing (apnea) for 10 seconds or longer during sleep. When your breathing stops, you may make grunting, gasping, or snorting sounds and restless body movements. As breathing resumes, loud snoring starts. This may happen many times during a night.

How many times you stop breathing while you sleep determines the severity of sleep apnea.

When you stop breathing, the oxygen levels in your blood go down and carbon dioxide levels go up. This makes your heart and blood vessels work harder and can affect your heart rate and nervous system. This in turn may lead to other problems including high blood pressure (hypertension) and coronary artery disease (CAD). Sleep apnea can also make these diseases worse and more difficult to treat. Sleep apnea also raises your risk of having a stroke.³

Because sleep apnea disturbs your sleep, it can make you very tired during the day. If you have sleep apnea, you may:

• Be more likely to have a car accident.
• Perform poorly at school or work and have difficulty concentrating. You also may have memory problems.
• Have personality changes, anxiety, and depression.
• Lose the desire for sex.

Certain factors make it more or less likely that you will have obstructive sleep apnea (OSA). Some of these you cannot change, while others you can.

Factors you cannot change

Factors that you cannot change and that may make it more likely you will have sleep apnea include:

• Aging. Sleep apnea is most common in people age 30 and older.
• Male gender. Sleep apnea is more common in men. Some studies have indicated that about 2 to 3 times more men than women have sleep apnea, and sleep laboratories report that 5 or 6 times more men than women have the disease.¹
• Family history. If other members of your family have sleep apnea, you are more likely to get the disease than someone who does not have a family history of the disease.
• Ethnicity. Blacks, Hispanics, and Pacific Islanders have a greater risk of sleep apnea than white people. Blacks get sleep apnea at a younger age than whites.¹
• Deformities of the spine. Deformities of the spine, such as scoliosis, may interfere with breathing and contribute to sleep apnea.
• Conditions that may cause head and face (craniofacial) abnormalities. Conditions such as Marfan's syndrome and Down syndrome may result in craniofacial abnormalities and increase the risk for sleep apnea.
• Menopause. Recent studies indicate that sleep apnea occurs more often in women who have been through menopause than in women who have not.¹ After menopause, women get sleep apnea at a rate similar to men.² Experts do not know why or how menopause increases the risk of sleep apnea.

Factors you may be able to change

Factors that you may be able to change that will reduce your chances of having sleep apnea include:

• Obesity. About 70% of people who have sleep apnea are obese.¹ Obesity is the factor most likely to lead to sleep apnea.
• Neck circumference. People who are overweight may have extra tissue around their neck, adding to their risk for sleep apnea. The risk increases for a man whose neck measures more than 17 inches around and for a woman whose neck measures more than 16 inches around.
• Enlarged tissues of the nose, mouth, or throat. Enlarged tissues in the nose, mouth, or throat can cause narrowing or blockage of the airway while you sleep, making sleep apnea more likely. Surgery can sometimes correct the blockage and improve sleep apnea.
• Bone deformities. Bone deformities of the nose, mouth, or throat can interfere with breathing, causing sleep apnea. Some people who have sleep apnea have a small, receding jaw. Surgery can sometimes correct these deformities and improve sleep apnea.
• Use of alcohol or medicine. Drinking alcohol or taking certain medicines before going to sleep can increase the risk for sleep apnea. These include sleeping pills and sedatives. Using Viagra (sildenafil) just before sleep also can make sleep apnea worse.⁴
• Sleeping on your back and using pillows. Sleeping on your back and using one or more pillows may make sleep apnea symptoms worse.
• Smoking. Smoking can increase your risk for sleep apnea because the nicotine that is in tobacco relaxes the muscles that keep the airways open.
• Poor sleep habits. Going to bed at different times or in different places may increase your risk for sleep apnea.
• Disorders of the hormone (endocrine) system. Disorders of the endocrine system (such as hypothyroidism and acromegaly) may increase your risk for sleep apnea.