My son is 4 yrs old and does not want to wear a nappy to bed, he says he is a big boy and wants to wear undies. His nappy at night was always very wet in the morning thought, which tells me that he is not developmentally ready but I do not want to discourage his excitement for going to bed in undies. Consequently, I have to wake him 2 times a night just to do a wee. Is there a better way..??