DIAPERS PROLONG BED-WETTING

A lot of bed-wetting goes back to the fact the child was never properly toilet trained at night. Diapers taught the child she could just let go in her diaper whenever she didn't feel like holding it, and now the brain is telling the bladder the same thing when the child is asleep. The child subconsciously knows she has a diaper on, so the brain tells the bladder, "Go ahead, the diaper will take care of it." If, however, the child wets and there is no diaper, she will wake up to the unpleasant feeling of wet pajamas and a wet bed. This will train the brain to tell the bladder to hold it until the brain can wake the child up and get her body on the toilet.

This article from the Journal Nature would seem to agree with me.