Your pillowcase has more bacteria than your toilet seat if you don't wash your sheets often
Each night, your body sheds around 15 million skin cells. If you never wash your sheets, they build up and provide food for hundreds of thousands of dust mites. But these arachnids aren't the only allergens in a dirty bed: Fungi and bacteria will also take root. In fact, one study found that your pillowcase has more bacteria than your toilet seat. Experts recommend washing your sheets with the hottest water possible once a week.