That sounds like the place doing the sleep study is pulling some stuff. When I had my study they had me sleep for awhile and then they woke me up and put the cpap on. Then I slept again and they adjusted (remotely) the cpap pressure until it was right. The whole thing was done in one night.
MNB,
It sounds like your experience was [to my knowledge] the exception, at least around here, because [as best I can recall] everyone I have seen [professionally] or talked to [personally] has had at least a 2 night deal, so that the sleep MD can review the data and develop a treatment plan, meet with you to talk about it, and then have a sleep trial to see 1) if C-Pap helps you not have apneic episodes, and 2) at what level it does, if any.
I wanted to see the data analysis before deciding to go along with C-Pap because 1) I did not have any symptoms I could attribute to sleep apnea [no daytime fatigue or narcolepsy, no HBP, no elevated BG, etc.] and 2) I wanted to know what they found re: my restless legs- which I knew I had, my wife testified I had [as she did apneic episodes], and I wanted relief from.
The downside was that they did find both, but wanted to treat and reassess the [moderate] apnea first and wait to treat the leg [actually whole body] [severe] symptoms to see if they improved with better sleep.
Although the NPLMD [Nocturnal Periodic Limb Movement Disorder- how's that for a mouthful] did not improve when I did the sleep trial with the C-Pap on, they thought it might over time.
To be fair, at the time I was also getting up 2 or 3 times each night to urinate, and although that did not improve on my overnight with the C-Pap either, now that I'm using it regularly, I rarely ever get up at all, [unless i have a beer too close to bedtime].
My sleep doc told me that might get better [I knew it wasn't my prostate, but didn't know it could be apnea-related], and I am happy it has.
My NPLMD [I'm really thinking about alphabetizing that acronym] has not apparently improved based on my AM body aches and my wife's reports, so I need to go back and talk to them about that too...
As for the nocturia [night time peeing- not in bed ;-0 ] the reason the sleep doctor gave for that made some sense to me, and it also helps account for some of the other negative things that untreated sleep apnea can cause.
Apparently the way our bodies arouse us to restart breathing is to circulate some adrenaline, which also increases the blood pressure and pulse rate, making more blood circulate through the kidneys = more urine sooner than normally.
With the C-Pap preventing the apnea so it is no longer causing the need for arousals, the blood flow, blood pressure, and pulse slow back down to normal, so less urine is made, and less arousals specifically for emptying the bladder are needed.
YMMV.