Obstructive sleep apnea is the most common type of sleep apnea. It is estimated to affect 10% to 30% of adults in the United States but in many cases remain undiagnosed. Obstructive sleep apnea (OSA) occurs when the upper airway gets blocked during sleep, which may cause snoring as air is prevented from passing through normally. In response to the airway obstruction, a person usually wakes up, engages the muscles in their throat, and takes several gasps or deep breaths, often accompanied by sounds like snorting or choking.