Diagnosed Aug 2007, I use RespCare Hybrid FFM with my trusty S9 APAP, annual AHI has been 0.1 for years.  New phenomena the past few months: large leaks, not every night but most, long enough leaks that it's driving up my pressure waking me up leading to feeling lousy the next day -- AHI all over the place, even some CAI which has always been pretty much nonexistent.  Swapped out all mask parts, hose.  Adjusted and re-adjusted new headgear.  Dragged out humidifier tank, got some distilled water, tried different settings -- not helping (nasal congestion has been pretty horrid..  Even swapped out the swivel connector (hose to mask) as I did feel a bit of air flow around it, reduced leak for that sleep session   

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Side sleeper, my pillow is pressing the mask against my face and I am getting occasional leaks on that side, maybe frequent if not constant after I fall asleep.  So I am looking for pillow suggestions.  I  have been using a contour memory foam pillow with the narrow side under my head (the large side is waaaay too high).  I am not yet willing to cut it up to create a channel for the mask.  What works for y'all?