An auto-titration pressure support system comprising: a pressure generating system adapted to generate a flow of breathing gas at a selectable pressure level; a patient circuit having a first end adapted to be coupled to the pressure generating system and a second end adapted to be coupled to an airway of a patient; a monitoring system associated with the patient circuit or the pressure generating system and adapted to measure a parameter indicative of a pressure at a patient's airway, a flow of gas in such a patient's airway, or both and to output a pressure signal, a flow signal indicative thereof, respectively, or both; and a controller coupled to the monitoring system and the pressure generating system, for controlling the pressure generating system based on the output of the monitoring system, characterised in that the controller is programmed to: determine whether the patient is experiencing an apnea/hypopnea based on the pressure signal or the flow signal, set a pressure treatment limit based on a pressure at a time an apnea/hypopnea is detected, cause the pressure generating system to increase a pressure of the flow of breathing gas delivered to a patient responsive to a current pressure being below the pressure treatment limit, and cause the pressure generating system to decrease a pressure of the flow of breathing gas delivered to a patient responsive to a current pressure being at or above the pressure treatment limit. a pressure generating system adapted to generate a flow of breathing gas at a selectable pressure level; a patient circuit having a first end adapted to be coupled to the pressure generating system and a second end adapted to be coupled to an airway of a patient; a monitoring system associated with the patient circuit or the pressure generating system and adapted to measure a parameter indicative of a pressure at a patient's airway, a flow of gas in such a patient's airway, or both and to output a pressure signal, a flow signal indicative thereof, respectively, or both; and a controller coupled to the monitoring system and the pressure generating system, for controlling the pressure generating system based on the output of the monitoring system, characterised in that the controller is programmed to: determine whether the patient is experiencing an apnea/hypopnea based on the pressure signal or the flow signal, set a pressure treatment limit based on a pressure at a time an apnea/hypopnea is detected, cause the pressure generating system to increase a pressure of the flow of breathing gas delivered to a patient responsive to a current pressure being below the pressure treatment limit, and cause the pressure generating system to decrease a pressure of the flow of breathing gas delivered to a patient responsive to a current pressure being at or above the pressure treatment limit. determine whether the patient is experiencing an apnea/hypopnea based on the pressure signal or the flow signal, set a pressure treatment limit based on a pressure at a time an apnea/hypopnea is detected, cause the pressure generating system to increase a pressure of the flow of breathing gas delivered to a patient responsive to a current pressure being below the pressure treatment limit, and cause the pressure generating system to decrease a pressure of the flow of breathing gas delivered to a patient responsive to a current pressure being at or above the pressure treatment limit.