 Mattress protector is full of bodily fluids. Even though it goes under your sheets, mattress protectors collect drool, urine, and the 26 gallons of sweat your body produces in your sleep each year. Cleaning the protector at least every other month helps keep your mattress safe from fungus and bacteria. It also significantly extends your mattress's lifespan. To clean it, just toss it in the washing machine on cold or even spot clean using detergent, water, and a cloth.