S.P.
First of all it is very NORMAL for a child especially a boy to have trouble controling their bladder at night even when they have been potty trained for many years. I have a 6 year old son as well who has to wear over night pull ups to bed. Each night he wets them. He is a very hard sleeper. (Can sleep through the fire alarm going off in his room.) The doctor states that once he gets 8 years and still can not control it then there are some medical type alternatives i.e. "potty pager" or medicine. Again the doctors state that there is nothing medically wrong with him. I also have a 4 year old son who has been potty trained both day and night since he was two. The doctor always says NOT to compare them as their bodies grow differently. For more facts just google it as it is VERY common... Hope that helps some.