A method is disclosed for operating a device that treats sleep disordered breathing (SDB) during successive treatment sessions, where the device provides continuous positive airway pressure during sleep. The method may include the steps of applying a constant treatment pressure during a first session, detecting SDB event(s) during the first treatment session and, in response to the detected event(s), adjusting the constant treatment pressure. During a setting procedure, a second constant treatment pressure is determined for a second treatment session which is subsequent to the first treatment session. The second constant treatment pressure is determined based on checking of a clock and the detected SDB event(S).