Different readings with different masks - is that normal?

[YDNAM]

I have changed from a full face mask to a nasal mask. Although the nasal mask is far comfier i have noticed a dramatic difference in the console readings. They have gone from an AHI of 8 (full face) to 1.2 (nasal) and periodic breathing of 4-5(full face) to zero with the nasal. Is it a coincidence that I am finding myself begin to doze again during the day? I noticed early on that my jaw was dropping open so used a neadband to keep my mouth shut (as advised by the sleep nurse) but this isnt affecting either my readings or sleepiness. Is it normal to get different readings from different masks or is my machine not doing what it should with a different mask fitting?

[Pugsy]

Sometimes people need a little more pressure with a full face mask.
Without knowing more about your data we don't know if that is the case in your situation.
It all depends on the AHI breakdown that you are having with a full face mask.

If you are having large leaks (mouth breathing or leaking a lot) with the nasal mask..over 90 L/min is large leak territory..then the machine might be simply missing sensing some events due to large leak but if your leak numbers are okay then we can trust the AHI.