During night time potty training, I came up with an idea to avoid middle of the night sheet changing by "doubling up". I made up the mattress like this: plastic fitted sheet, regular cotton sheet, plastic fitted sheet, cotton sheet. When my child had an accident at night, I only had to remove the top layer (cotton and plastic sheet) and the bed was ready to sleep in. It was much quicker then making up a dry bed and helped us all get back to sleep quicker!