Puzzled??????

I have a question that I am wondering if anyone can explain. I am a newbie to CPAP use and my Doc. prescribed a FF mask from the "get-go" after my second sleep study and titration. However, at my first sleep study they put a nasal mask on me about mid way through the night and I slept better for the rest of the night. I remember driving home that next morning and feeling so much better. AFter the second study I remember driving home feeling spacey and lightheaded. Anyway, since beginning my at home use of CPAP I was using a FF mask and feeling "unwell" in the mornings, spacey and lightheaded. Last week my DME suggested I might try the nasal mask again and use a chin strap to close my mouth(since I have been a mouth breather for years). I tried the nasal mask and from the first night I noticed I felt better in the morning,not spacey and an overall feeling of having rested better. I actually taped my mouth with micropore tape at night. Why would this happen? What about using the nasal mask would create a better feeling (since my doc says a FF is very important for me ).? Do you think the FF is leaking too much or not giving me enough pressure since it escapes through my mouth? I am very curious about this and would like to address my doc about it but she had to rearrange my upcoming appt. til Jan. 8. Any thoughts on this ??

That is why it's important to get the software needed to check on your progress. Different things we do have different results, without the software it becomes more confusing. Jim