Obstructive and central sleep apnea differ in their causes and risk factors and are distinct disorders. Most people with obstructive sleep apnea do not have trouble with blockage of breathing while they are awake. However, once they fall asleep a number of changes occur that all contribute to obstructive sleep apnea. Muscle relaxation and changes in muscular reflexes allow structures like the roof of the mouth (soft palate) and tongue to collapse and block the space for breathing in the throat.
The control of breathing also changes during sleep, affecting the body’s response to the blockage of breathing and the decreases in oxygen and increases in carbon dioxide that occur in the bloodstream. There are a number of other changes, including the fact that people typically sleep lying flat and also take smaller breaths during sleep. All of these play a role in obstructive sleep apnea, to a different extent in different people.
What Are the Risk Factors for Obstructive Sleep Apnea?
1. Enlargement of the tonsils or adenoids: This is a common cause in children, but can also occur in adults.
2. Weight gain: Overweight and obese individuals are more likely to have obstructive sleep apnea. Studies have shown that fat can be deposited within the tongue and around the throat, especially in those with sleep apnea. This fat deposition narrows the space for breathing in the throat and increases the chance of having obstructive sleep apnea.
3. Male gender: Obstructive sleep apnea is two to three times more likely in men than women, even after correcting for other differences (for example, men tend to have greater rates of obesity). Also, the increased amounts of estrogen and progesterone in women offer protection against obstructive sleep apnea.
4. Facial structure: Those with certain facial structure features, such as a small lower jaw (mandible), are at increased risk of obstructive sleep apnea.
5. Aging: The likelihood of an adult having obstructive sleep apnea increases with age, remaining at approximately 40 percent in women and men over 60 years of age. It is unclear whether this is solely related to aging or whether it is the result of weight gain over time.
6. Family history: There appears to be a genetic basis to obstructive sleep apnea.
What Are the Causes and Risk Factors for Central Sleep Apnea?
1. The different types of central sleep apnea have different causes and risk factors. And in some cases there are no obvious causes.
2. Cheyne-Stokes respiration is a pattern of irregular breathing that occurs most often in individuals with congestive heart failure. The precise cause of the sleep apnea is unknown, although it appears to be related to changes in the control of breathing due to the increased amount of time it takes blood to circulate through the body in patients with congestive heart failure.
3. Another type of central sleep apnea is caused by a pattern of periodic breathing, which typically only develops when these individuals go to a high altitude. In some patients, however, periodic breathing may occur at normal elevations if they are predisposed to the condition.
4. Other known risk factors for central sleep apnea are acid reflux, postnasal drainage, narcotics use and alcohol consumption. But for many people there is nothing specifically identified as a direct cause of their central sleep apnea.