M.C.
i used to babysit for a girl who had a similar problem. she was wetting the bed constantly and they finally found out that her bladder muscles hadn't formed correctly and they were just too weak. it wasn't a problem during the day because she could feel the need and go to the bathroom. it was only a problem at night. she was put on medication for several years and the muscles eventually strengthened. She is now 14 and no longer takes the medication or wets the bed.