Adult size plastic pants are available that will let you sleep through the night with out wetting your mattress. Google will help you find what you are wanting.
I wear them and sleep knowing I may wake up wet, but my mattress is dry.
There are vinyl mattress pads. Plus the various disposable incontinence pads (chux pads). What is Your level of incontinence ? Do You wear a pad or brief (diaper) All these questions can help answer Your question.