S.,
I had the same thing with my daughter. I went to her pediatrician for advice. She told me to get her out of the diapers (pull-ups really are the same as diapers). She said she may be waking up because of needing to urinate, but she doesn't have to because of the pull-ups. She said try taking her to the bathroom before I go to bed and if she does wet the bed, make her help me change the bedding. Well, I was getting her up and if she had peed already, I made her help me change.
Well, I don't think she ever was fully awake and knew what she was doing. So, I quit getting her up and just let her go if she had to and helped her clean up. Well, she got smart and if she peed, she got up and changed her clothes and put the blankets over it and slept on them (it was summer so she didn't need them over her). When I realized this, I took the blankets off the bed so she had to get up to change sheets at least. Well, it didn't take long after that, and she was sleeping dry all the time.
By the way, later I found out that one time she had a good friend spend the night and told her to ask to wear a pull-up so she didn't have to get up at night to use the bathroom.
Hope this helps.
L.