Fitness trainer Kayla Itsines recently shared a makeup-free selfie and details about her skincare routine on Instagram. We were surprised to learn that the 24-year-old social media star credits her gorgeous glow to her pillowcase: "I LOVE looking after my skin and making sure it's always clean and fresh," she wrote. "I do this by changing my pillow case [sic] every 3 days."

As someone who switches her pillowcase once a week (at most...), my first thought when I read this caption was Seriously? Yet another nighttime skincare step I have to worry about? But Itsines may be on to something: Experts say if you have acne-prone skin, cozying up to clean fabric at night may help keep your complexion clear.

"Dirt, bacteria, and often makeup collect on a pillowcase," says Debra Jaliman, a New York City-based dermatologist and creator of the Sea Radiance skincare line. To prevent new breakouts from developing overnight, she recommends switching your pillowcase anywhere from every few days to daily (more often if you regularly wear makeup or are particularly acne-prone.)

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And yes, these guidelines apply even if you wash your face right before bed each night. After cleansing, "there will still be oil and bacteria on the skin," Dr. Jaliman explains. 

The type of pillowcase you use matters, too. Although silk pillowcases are often recommended for fighting fine lines and frizz, a breathable fabric like cotton may be better when it comes to preventing breakouts. Look for a brand that's made from 100% cotton, such as Utopia Bedding 100% Cotton Pillowcases ($30 for a dozen; amazon.com). They come in packs of 12, so you'll have plenty of spares to last you until next laundry day. 

Also important: When washing your pillowcase, "it's better to use fragrance-free detergent and to avoid fabric softeners," says Dr. Jaliman. This is especially true if you have sensitive skin; opt for a dye-free, fragrance-free formula (they'll often have the phrase "free and clear" on the label).