1st just to qualify I'm not a doctor...just a long term nocturia suffer. I've been battling a sleep disorder for about 10 years now. After 2 false negative sleep studies (there was no way I could sleep in the lab) in fact I even got diagnosed with narcolepsy!!! The day after one of my sleep test they gave me a multiple sleep latency test (MSLT)...and did the narcolepsy diganosis. It defied logic to me as I told the doc of course I'd fall asleep quickly after not sleeping the night before...but I guess that's another story.
Anyway I've been taking 'Desmopressin' nasal spray at bed time for several years now. Its not a bladder control med its an anti diuretic med. Google treatment of nocturia with desmopressin as it's becoming a mainstream treatment....I convinced my family doc to try it several years ago after all the urology and sleep test came up negative. I came across a article in the British journal of urology about using it for nocturia and presented it to him in desperation after getting up 5-6 times per night to go. It's typically used in kids that wet the bed or those with other urological disorders. Anyway we gave it a try and it worked!...6xs a night down to 1 or 2xs a night. Good thing I had an open minded dr...anyway be prepared to gain some water weight at first and they have to monitor your salt levels regularly.
Now the good news...two months ago I talked my sleep dr into doing a home sleep test....we did a 3 day at home sleep test and bingo the osa showed up...not severe but mild and with Oxy desats down into the low 80s several times a night.....I started APAP 3 weeks ago....I've been monitoring my results and things are looking way up....I still have mild daytime sleepiness but I don't have the fatigue and feeling that I got ran over by a truck the night before. I'm guessing that feeling came from the low oxy levels. Anyway I'm looking forward to the next few weeks as life steadily improves...and I'm weaning myself off the desmopressin as I believe we've finally found the root cause of the nocturia, in addition, to the irregular heartbeat, high blood pressure, and fatigue.
Take care and make sure your OSA is under control and cpap set right before going the medication for nocturia route.
Oh by the way my uncle used to call me the camel...I'd hold my water all day and release it all night!