Several things can be done, but it is important and essential to understand why the problem is occurring, and not shame or punish the child. In most cases. Most children outgrow the issue as their brain develops as they get older. Most children simply do not have the 'brain alarm' that wakes them when their bladder is full. Limiting fluids after the evening meal is a standard measure. Then be sure to put waterproof sheets or better yet, and waterproof cover over encasing the entire mattress so that the mattress is not damaged. Then, place several layers of old blankets onto the bed, and cover with the bed sheet. Should the child wet, it is then easy to strip off the sheet and remove the layers of blankets that are wet, replacing a fresh sheet. In the morning, have the child wipe down the plastic mattress cover with antiseptic spray and take their wet blankets and sheets to the laundry. Then, have them bathe. Do not do this in a punitive manner, but in a matter-of fact way. The entire process becomes tedious to the child, serving to act as a natural consequence that can motivate the child to learn to stop the behavior. If these measures do not work, there are medications that can help.