How old is your son?
Is it dirty with pee or poop?
For any messes/leaks....I would use a waterproof bed pad.
You can find many at www.amazon.com
And it makes clean up a lot easier and you won't have to wash the entire bedding, just the bed pad.
Often, older babies or younger toddlers go through this and take off their diapers. It passes but each child is different.
Both my kids went through this, but at about a year old....and they were not ready for potty training.
Mostly, for my kids, it was because they "know" they could take off the tabs of their diaper when they pee or poop or whenever... because all this time they have watched us do it. And mostly my kids thought it was funny! But luckily, this "phase" did not last long in my kids.
I just told them "no..."
My kids did it whenever, anytime of day.
You could try and put onesies on him or shorts over his diaper...or some clothing that covers his diaper... or even overalls. Then he can't get to his diaper to take off the tabs himself.
Or, you check his diaper at night and change him, cutting to the chase so to speak.
Or, there are waterproof diaper covers too...
Good luck,
Susan