Do you need a second pillowcase?

Expert insight:

Dust mites thrive in warm, humid environments and survive off of dead human skin cells. Your bedding is the perfect place for them to post up since you make it warm every night and leave behind cells.

Snug, zippered covers can reduce your allergic reactions since dust mites are too large to penetrate them, says Morris Nejat, MD, chief medical officer of NY Allergy & Sinus Centers in New York City.

The bottom line:

If you have dust allergies, place a zippered cover over your pillow and mattress first, then layer your fitted sheet and regular pillowcases on top. This will help you breathe more easily while you sleep.

Wipe the covers with a damp cloth every two weeks, Nejat says. Wash the rest of your bedding weekly in water that’s at least 130 degrees F, hot enough to kill dust mites.