The neurological control of bladder function and the ability to be dry at night involves not only the acquisition of normal daytime control, but also the establishment of a circadian rhythm in vasopressin release and the ability to arouse to a full bladder during sleep. We postulated that in some children there might be a delay in maturation of the normal neurological pathways involved in establishment of nocturnal continence and examined this by using a specific neuropsychological test.