A Continuous Positive Airway Pressure (CPAP) device is a machine that sends pressurized airflow into your nose and mouth as you sleep. This makes it easier for you to breathe by keeping your upper airway open. CPAP therapy is effective if you have been diagnosed with obstructive sleep apnea. As you sleep, the airstream from the CPAP machine pushes against any blockages, opening your airways so your lungs receive plenty of oxygen. Without anything obstructing this flow of oxygen, your breathing doesn’t pause. As a result, you don’t repeatedly wake up to resume breathing.