Now the question is, what will happen to use a dirty bedsheet? According to Experts, oil, dead skin cells and sweat are deposited from your skin on the bedsheet. The dirty sheet has a home of bacteria and fungus, which can cause problems like itching, acne, rashes. Dust and dust mites on the bedsheet can increase respiratory diseases. This can lead to allergies, sneezing, nose flow and asthma attacks. If you have some kind of injury or cut in your body, bacteria from dirty sheets can penetrate there. This can cause skin infection or system.