Doesn't happen often, but when it does, it's memorable.
The other night it was quite cold out; I got into bed and got nice and comfy and warm. Sometime in the middle of the night, I felt the urge to pee. I didn't want to get out of bed, so I just lay there, thinking the urge will go away. I, eventually, went back to sleep. I remember dreaming about having to pee so badly, frantically searching for a potty. I was holding myself, all the while thinking "I got to pee".
Shortly thereafter, I started to wake up and realized I wasn't dreaming, but slowly wetting the bed. I still didn't want to get up, so I turned on my back(I was sleeping on my side)and just continued emptying my bladder into my panties. It felt so good and was so warm. I had a giant wet spot on the bed; I finished peeing, turned over and went back to sleep. Slept like a baby the rest of the night.