Knowing how often to wash bedding is as important a question as how to wash bed sheets themselves. Dirt and dust can quickly build up and, while deciding how often to wash bed sheets might be a matter of personal preference, unfortunately we’re not alone in our beds—we settle down at night with microscopic dust mites, among other things.

Dust mites aren’t the only hidden surprises lurking in our sheets, and unfortunately we’ve only ourselves to blame for their presence. Every night we shed a million skin cells, accompanied by oil and sweat. If you don’t wash your bedding regularly, this adds to your bed’s appeal for mites—but is less than pleasant for human occupants.

So, How Often Should You Wash Bed Sheets?

As a general rule, it’s a good idea to wash your sheets and pillowcase once a week or every two weeks. Not washing your bedding regularly can contribute to increased suffering from health problems such as allergies and asthma. If you, your partner, or your child is unwell, make sure to wash your bedding daily or, at a bare minimum, change the pillowcase every day that they are in bed ill.