Hi Lee,
The answer to your question is that the intestines do their thing 24/7, not just while you're awake. You have 22' of bowel for a reason.....all that surface area can absorb nutrients while they're passing by. Your bowels also expand as they fill, so while you're sleeping your small intestine is busy absorbing nutrients and recycling your bile, while your colon is busy absorbing water and acting as a trash compactor so you don't have to be on the toilet all the time. When you remove part of that system you screw up the timing, and what ends up coming out of you and when. For example, I have about 3 1/2 feet of small bowel left and my colon is disconnected......so that 3 1/2 feet has to do all the work of what used to be 22 feet of bowel. It does a decent job, but physics is physics and if you dump something into one end of a 3 1/2 foot garden hose it's going to come out the other end much faster than if you dumped that same stuff into a 22 foot long garden hose. So pretty much whatever I eat is out of me in less than 2-3 hours. If I still had my full 22 feet of bowel that could take 24 hours or more. And that makes sense by the simple math.....3 feet gives me 3 hours, so 22 is about 7 times more bowel, and 7 times 3 hours is 21 hours. So unless your bowels are truly empty.........you're going to have output. Also, don't forget that your bowels have two valves that help regulate flow. One at the end of your small bowel, called an ileocecal valve that controls what flows into your colon, and then your sphincter in your rectum, which allows you to hold more in your colon until you can find a toilet. Most ostomy patients have one or both of those valves either removed on no longer active.....so there's no longer any control of your bowel flow by your body. Remember that your stoma is only the very end of whatever parts of your bowel you have left, so it's not a good indicator of what the rest of your bowels are doing upstream. So the tail of the dog could be wagging while the head of the dog is falling asleep..........if you know what I mean.
In your case the end of your bowel is doing its thing at night. You can adjust that by when you eat. That might not be practical or desired, but with critical parts of our bowels missing........we're pretty much along for the ride at this point. Of course WHAT you eat also determines how fast it travels thru your body, so maybe you should find a good dietician who specializes in IBD, and not diabetes or obesity, and see what they say. One word of caution.......MOST dieticians have NO experience with people like us.....so if they don't specialize in IBD patients.......stay clear. Your Gastro should be able to get you in touch with a qualified dietician. Lastly, a Nutritionist and a Dietician are NOT the same. You want a Dietician.
Hope that helps,
Bob