A system includes an apparatus and a controller, according to an embodiment. The apparatus is configured to maintain an airway of a subject open while the subject is sleeping by applying to the airway a pressure having a magnitude, and the controller is configured to cause the apparatus to change the magnitude of the pressure over a period that begins at a settable start time. For example, the system can be configured to treat a subject's sleep apnea with positive or negative pressure, and to function as an alarm clock by beginning to change the pressure magnitude at a settable start time, and to continue changing the pressure over a period with a settable duration (or settable stop time) to gently awaken the subject by the end of the period.