Abstract: Methods and system for treating obstructive sleep apnea and snoring are disclosed. The system generally comprises a mask for delivering pressurized air to patient's breathing orifice, a sensing mechanism for continuously assessing the state of patient's breathing and a pressure generator for generating the pressurized air in the mask. The pressurized air is applied to the breathing orifice only during selected portions of the breathing cycle, when such pressure might be required to prevent occlusion of the airway or to restore patency of the airway after such occlusion occurs.