Before I started the CPAP machine, I would wake up in the middle of the night needing to go to the bathroom. Now with CPAP I still wake up a couple of times a night, but don't have to go to the bathroom like I used to, so I don't until I get up for good in the morning.

What's up with this? CPAP has made my bladder bigger and/or stronger? LOL - Does anyone understand what is happening here?

It's called nocturia; there are many posts here about it. I had it bad when I was at the peak of my pre-BIPAP OSA. I used to get up at least six times (my record is nine), and had several accidents because my bladder would fill almost as quickly as I emptied it.    It's got to do with the buildup of carbon dioxide in the bloodstream, and your kidneys have to work overtime to eliminate it because you're not exhaling it. Since I've begun treatment, I never get up during the night anymore.


_________________
ResMed VPAP III machine, bilevel at 22/16
ResMed Activa Mask

The phenomenom of waking up during the night before treatment and then sleeping through is common. I had the opposite. I always slept through the night until put on CPAP, then I started waking up several times during the night from being unused to the new sleep situation. I didn't need the bathroom, but I was often confused as to whether it was morning or not and sometimes was halfway dressed before I realized it was the middle of night.
After 8 or 10 months on the CPAP, I started sleeping through the night more often than not.


_________________
Arthur
Sleeping with a curvaceous blonde autoPAP (Resmed autoset). Hope springs eternal.....

How interesting. First I've learned about nocturia.

It is. I had no idea that my frequent bathroom visits were connected to my apnea. I thought I was drinking too many liquids before bedtime, but cutting down didn't reduce my "output."    I didn't know at the time I even had OSA, much less what symptoms it produces.


_________________
ResMed VPAP III machine, bilevel at 22/16
ResMed Activa Mask