Sleeping With Pillows and a Mattress The average person sheds about 1.5 million skin cells per hour and perspires one quart every day even while doing nothing, says Tierno. The skin cells accumulate in our pillows and mattresses and dust mites grow and settle. If that's not gross enough for you, Tierno explains that a mattress doubles in weight every 10 years because of the accumulation of human hair, bodily secretions, animal hair and dander, fungal mold and spores, bacteria, chemicals, dust, lint, fibers, dust mites, insect parts, and a variety of particulates, including dust mite feces. After five years, 10% of the weight of a pillow is dust mites. This is what you're inhaling while you sleep. "What you're sleeping on can exacerbate your allergies or your asthma," says Tierno.Solution: Cover your mattress, box springs, and pillows with impervious outer covers. "Allergy-proof coverings seal the mattress and pillow, preventing anything from getting in or out, which protects you," Tierno says. He also suggests that you wash your sheets weekly in hot water. Make sure the temperature range of the water is between 130 to 150 degrees Fahrenheit.