Causes of Obstructive Sleep Apnea
Obstructive sleep apnea is a common and serious disorder in which breathing repeatedly stops for 10 seconds or more during sleep. The disorder results in decreased oxygen in the blood and can briefly awaken sleepers throughout the night. Sleep apnea has many different possible causes.
In adults, the most common cause of obstructive sleep apnea is excess weight and obesity, which is associated with soft tissue of the mouth and throat. During sleep, when throat and tongue muscles are more relaxed, this soft tissue can cause the airway to become blocked. But many other factors also are associated with the condition in adults.
In children, causes of obstructive sleep apnea often include enlarged tonsils or adenoids and dental conditions such as a large overbite. Less common causes include a tumor or growth in the airway, and birth defects such as Down syndrome and Pierre-Robin syndrome that cause enlargement of structures such as the tongue and jaw. Although childhood obesity may cause obstructive sleep apnea, it's much less commonly associated with the condition than adult obesity.
Regardless of age, untreated obstructive sleep apnea can lead to serious complications, including cardiovascular disease, accidents, and premature death. So it's important that anyone with signs and symptoms of obstructive sleep apnea -- especially loud snoring and repeated nighttime awakenings followed by excessive daytime sleepiness -- receive appropriate medical evaluation.
Other Risk Factors for Obstructive Sleep Apnea
In addition to obesity, other anatomical features associated with obstructive sleep apnea -- many of them hereditary -- include a narrow throat, thick neck, and round head. Contributing factors may include hypothyroidism, excessive and abnormal growth due to excessive production of growth hormone (acromegaly), and allergies and other medical conditions such as a deviated septum that cause congestion in the upper airways.
In adults, smoking, excessive alcohol use, and/or the use of sedatives is often associated with obstructive sleep apnea.
Obstructive Sleep Apnea and Overweight
More than half of people with obstructive sleep apnea are either overweight or obese, which is defined as a body mass index (BMI) of 25-29.9 or 30.0 or above, respectively. In adults, excess weight is the strongest risk factor associated with obstructive sleep apnea.
Each unit increase in BMI is associated with a 14% increased risk of developing sleep apnea, and a 10% weight gain increases the odds of developing moderate or severe obstructive sleep apnea by six times. Compared to normal-weight adults, those who are obese have a sevenfold increased risk of developing obstructive sleep apnea. But the impact of BMI on obstructive sleep apnea becomes less significant after age 60.
BMI isn't the sole marker of obesity that's important. Men with a neck circumference above 17 inches (43 centimeters) and women with a neck circumference above 15 inches (38 centimeters) also have a significantly increased risk of developing obstructive sleep apnea.