Someone told me this tip when I was pregnant with my DD and it saved many many nights of what could have been HOURS of lost sleep, instead just about 30 minutes.
Kids puke, diapers leak, and when potty training kids pee the bed (crazy right?). That being said, when these things happen in the middle of the night, it requires you to strip the bed and remake it, and also to change the baby.
What we did was made the bed this way: Mattress cover, sheet, mattress cover, sheet. This way, if my DD had an accident, got sick or whatever, DH would change her clothes, and I would take off the top layer of sheets. Then we would lay her back down on the already made bed.
Saved us many nights of having to remake everything in the bed.