An alarming 80% of patients with moderate to severe obstructive sleep apnea (OSA) are undiagnosed and untreated before surgery. OSA occurs when the soft tissue in the back of the throat narrows and repeatedly closes during sleep. The brain responds by waking the person up, and breathing resumes. Those with OSA can stop breathing hundreds of times each night, resulting in ineffective sleep. Without proper treatment, OSA can cause high blood pressure, cardiac disease, impotence, and other problems.