Step 1
Remove the mattress cover from your Sleep Number mattress. If the mattress cover is contaminated with mildew, clean it in the same manner you clean the mattress itself. The Sleep Number company does not advise machine-washing its mattress covers.
Step 2
Move the Sleep Number mattress outdoors to dry. If you lack the necessary sunlight to dry the mattress thoroughly, accelerate the drying process using a heating device or a couple of high-powered fans to draw moisture away. Do not proceed until your Sleep Number mattress is completely dry.
Step 3
Vacuum your Sleep Number mattress to remove the dry mold spores. If you do not draw out the spores themselves, the mildew can begin to regenerate at the first sign of new moisture. Use the hose extension to reach the thin crevices of your Sleep Number mattress.
Step 4
Place a few drops of liquid detergent into a bucket of water and apply the soapy water to a sponge. Scrub the surface of your Sleep Number mattress with the sponge, wherever mildew appears. The Sleep Number company does not recommend using any solvents other than detergent for spot cleaning, but liquid detergent can prove highly useful against mildew, because liquid detergents contain disinfecting agents such as phosphoric acid.
Step 5
Dry your Sleep Number mattress and return it to its original location indoors. Place the mattress cover over the mattress. Keep the mattress dry to prevent new mildew from forming.