I deal with this all the time in my profession, but not necessarily when it comes to using gear.

Prostate - possibly, but you'll prob have day time symptoms. obstructive symptoms: hesitancy, intermittency, postvoid dribbling, yada yada. Irritative symptoms including urgency, frequency. SOME men I see have BPH with mainly nocturnal symptoms, but that's rare.
Water retention - when you lay flat at night, fluid goes back to the heart, then the kidneys
Cortisol
Do you have sleep apnea? Can release atrial natriuretic peptide causing nocturnal polyuria
drinking too much fluid before bed.
Diuretic use - people on HCTZ or lasix for their HTN, CHF, liver failure or kidney disease

With gear use, The game is probably changed. I bet there's a change in ddAVP secretion with gear use, or some people may develop some type of nocturnal resistance to it...but that is pure speculation on my part.

Also if you're just waking up more frequently at night for other reason, most people will void. Pretty normal.

Are they large volume voids at night or small?

lots of things to consider

I have no medical reason but for me. When i listened to a few guys at the gym i started eating cottage cheese before bed. After the 2 nd night i started peeing about 4 to 5 times a night. Tried it for a week then stopped cottage cheese and went back to my 1 time a night pee.

cortisol.

When your heart is stressed it releases peptides that act as diuretics that make you wake up to piss at night. Causes of this could be sleep apnea makes heart rate stay up instead of at a good resting rate, pulmonary hypertension, hypertension and last but not least CHF congestive heart failure. Not trying to scare you but if you don't go to the doc and find out the root problem, you're going to have some big health problems pretty soon. My # 1 bet is that it's sleep apnea.

Water intake? Prostate?