If you have a urostomy, you will attach a night drainage bag to your pouch and so will not need to get up to empty the pouch during the night.
People who slept on their back prior to having stomal surgery, continue to sleep on their back easily. In the beginning, when the abdomen is sore, putting a small pillow under the knees will help release tension from the abdominal and lower back area. People who are used to sleeping on the side, may find it easier to sleep on the side where their stoma bag isn’t, they could use a pillow to support their abdomen and help avoid rolling forward too far and one knee up also stops them from rolling too far forward on the abdomen and constricting their pouch. People who are used to sleeping on their stomach, might need to retrain their body out of it, to avoid constricting their pouch during the night.