A pressure support system, comprising: a pressure generating system (52, 60) adapted to produce a flow of gas; a patient circuit (56, 58) operatively coupled to the pressure generating system to deliver the flow of gas to an airway of a patient; and a controller operatively coupled to the pressure generating system, wherein the pressure support system is arranged to monitor the patient's response to pressure changes in the flow of gas delivered to the patient, the controller being adapted to control a pressure of the flow of gas by: detecting an occurrence of a sleep disordered breathing event in the patient; and in response to the detecting, performing one or both of: (i) determining whether an airway of the patient is open or closed, and (ii) determining whether the sleep disordered breathing event is centrally mediated; in response to determining (i) that the airway of the patient is closed, or (ii) that the sleep disordered breathing event is centrally mediated, or in response to (i) that the airway of the patient is closed, and (ii) that the sleep disordered breathing event is centrally mediated: determining whether the patient has been responsive or non-responsive to previous monitored pressure increases, and in response to the patient having been non-responsive to previous monitored pressure increases decreasing the pressure of the flow of gas provided to the patient or not changing the pressure of the flow of gas provided to the patient, wherein the patient is non-responsive to previous monitored pressure increases if the previous monitored pressure changes have occurred without resolving apnea events or have caused apnea events to turn into hypopnea events. a pressure generating system (52, 60) adapted to produce a flow of gas; a patient circuit (56, 58) operatively coupled to the pressure generating system to deliver the flow of gas to an airway of a patient; and a controller operatively coupled to the pressure generating system, wherein the pressure support system is arranged to monitor the patient's response to pressure changes in the flow of gas delivered to the patient, the controller being adapted to control a pressure of the flow of gas by: detecting an occurrence of a sleep disordered breathing event in the patient; and in response to the detecting, performing one or both of: (i) determining whether an airway of the patient is open or closed, and (ii) determining whether the sleep disordered breathing event is centrally mediated; in response to determining (i) that the airway of the patient is closed, or (ii) that the sleep disordered breathing event is centrally mediated, or in response to (i) that the airway of the patient is closed, and (ii) that the sleep disordered breathing event is centrally mediated: determining whether the patient has been responsive or non-responsive to previous monitored pressure increases, and in response to the patient having been non-responsive to previous monitored pressure increases decreasing the pressure of the flow of gas provided to the patient or not changing the pressure of the flow of gas provided to the patient, wherein the patient is non-responsive to previous monitored pressure increases if the previous monitored pressure changes have occurred without resolving apnea events or have caused apnea events to turn into hypopnea events. detecting an occurrence of a sleep disordered breathing event in the patient; and in response to the detecting, performing one or both of: (i) determining whether an airway of the patient is open or closed, and (ii) determining whether the sleep disordered breathing event is centrally mediated; (i) determining whether an airway of the patient is open or closed, and (ii) determining whether the sleep disordered breathing event is centrally mediated; in response to determining (i) that the airway of the patient is closed, or (ii) that the sleep disordered breathing event is centrally mediated, or in response to (i) that the airway of the patient is closed, and (ii) that the sleep disordered breathing event is centrally mediated: determining whether the patient has been responsive or non-responsive to previous monitored pressure increases, and in response to the patient having been non-responsive to previous monitored pressure increases decreasing the pressure of the flow of gas provided to the patient or not changing the pressure of the flow of gas provided to the patient, wherein the patient is non-responsive to previous monitored pressure increases if the previous monitored pressure changes have occurred without resolving apnea events or have caused apnea events to turn into hypopnea events. determining whether the patient has been responsive or non-responsive to previous monitored pressure increases, and in response to the patient having been non-responsive to previous monitored pressure increases decreasing the pressure of the flow of gas provided to the patient or not changing the pressure of the flow of gas provided to the patient, wherein the patient is non-responsive to previous monitored pressure increases if the previous monitored pressure changes have occurred without resolving apnea events or have caused apnea events to turn into hypopnea events.