Obstructive Sleep Apnea (OSA) is a sleep breathing disorder in which a person stops breathing while they sleep. The tissues in the throat collapse, cutting off the airway despite efforts to breathe. Apnea is defined as "a cessation of airflow for 10 seconds or more." This can occur dozens and sometimes even hundreds of times an hour. Typically, someone with sleep apnea snores heavily, and then stops breathing while still sleeping. A sleeping partner would observe that the person is struggling to breathe but there is no snoring sound. These periods of stopped breathing are followed by a gasping or choking sound. The person with sleep apnea will partially awaken in order to breathe, leading to fragmented, non-refreshing sleep which can be the cause of excessive daytime sleepiness. The even greater concern is that when the airway collapses and oxygen is cut off, the body goes into a fight-or-flight response, putting a strain on the heart and increasing blood pressure. Over time, this can wear out the heart and lead to heart disease or a stroke.