I have moderate OSA and used Fisher & Paykel Icon and their ThermoSmart 640 for 4 years in all. Now I am trying Somnetics Transcend CPAP, which seems good, with Respironics ComfortGel Blue nasal CPAP mask with headgear, which I soon became comfortable with. As it stands today, HME (waterless): Excellent Pressure & Accomodation: Very Good Size & Weight: Super I notice the machine, though a CPAP, starts off in a hunting or pulsing mode. It steadies by the evening, when it syncs with my breathing. I am trying to understand how this can happen. If anyone here is using the kind of CPAP and observed something similar, please let me know. Thank you very much in advance.