Urine Retention (nocturia): Why am I producing so much urine at night?

Hello,

Per my doctor, I am an otherwise healthy 40 something year old male who was been diagnosed with urine retention and voiding dysfunction (approximately six weeks ago). I've had a cystoscopy, which confirmed I have a very tight external urethral sphincter muscle and a hypertrophic bladder. I was doing self-catherization for over a month and pelvic floor stretches. I opted to have a foley catheter for the next month to relax the sphincter and bladder. I am awaiting a urodynamic study for further details, but its over two months out.

I am drinking 100 ounces of water or more each day per my urologist. I drink over half of the total in the mornings, and taper off through the afternoon. I stop drinking fluids at 6pm.

However, I noticed I am producing more than half of my daily output of urine between 11PM - 5AM, even though I empty myself before bed. When I was self cathing, I would void 300-400 ml on my own and cath another 400-700ml at night! When I wake up with my foley cath, I consistently have over 1000ml in my nigh bag. I asked my urologist and doctor why my urine output is so high at night and they do not know.

WHY am I producing so much urine at night?

Prior to the urine retention problem, I would get up once at night to pee 2-4 times a week, and my prostate is fine. I occasionally snore and my wife has not noticed any issues with breathing during sleep. I was tested for sleep apnea three years ago and it was negative. I exercise at least five days a week and was in the best shape of my life prior to the retention issues.

Could this be hormonal or neurological? Does the fact I worked a swing shift for fourteen years (off at midnight-ish) influence this?

How can I get my urine production to increase during the day and decrease at night?

Please help! I'd like some type of guidance so I can get my life back on track...