Last year, findings from a British survey of more than 2,000 people showed that over half of them slept on dirty sheets. (“Dirty” equals sheets not changed once each week.)

But besides the unclean feeling generated by this statistic, there’s an even a bigger issue. If you snipped a piece of cloth from those soiled linens and placed it under a microscope, you’d probably find dust mites in addition to the bacteria-laden skin our bodies shed that these icky bugs feast on. You’d also likely find excrement from the tiny critters.

Health problems caused by these invisible squatters are allergic diseases, such as asthma and rhinitis, a.k.a. hay fever. One study years ago suggested that over 45 percent of bedding in U.S. homes contained dust mite allergen concentrations exceeding a level associated with triggering allergic reactions.

According to the American Academy of Allergy, Asthma and Immunology, it’s essential that we encase mattresses, box springs, comforters and pillows in special allergen-proof fabric covers or airtight, zippered plastic covers. Wash bedding each week in water heated to at least 130° F, then tumble linens in a hot dryer.

Now, get some sleep!