It’s time for some pillow talk. And no, we’re not talking about bedtime conversations with your special someone. It’s actual pillows we’re interested in. When was the last time you replaced yours? If you can’t remember, you’re not alone; pillows are an afterthought for most of us. “I’ve been doing sleep medicine for 22 years, and no one has ever asked me a question about pillows before,” says Rafael Pelayo, M.D., a sleep specialist at Stanford’s Center for Sleep Sciences and Medicine.

Nancy Rothstein

Even pillows that pass the fold test and ones that look like they’re in good shape (no yellow sweat stains) are probably hiding buildup of body oils, dead skin, and dust mites. And after spending almost a third of each day laying on our pillow (some of that tossing and turning), the filling inside will break down over time. So it’s wise to replace your pillows with some regularity.

“If you have a plain-old, inexpensive polyester pillow, you should be replacing it every six months,” says Michael Breus, Ph.D., a clinical psychologist and author of the book Good Night. “But if you have a memory foam pillow or any one with structural integrity, it’ll last you anywhere from 18 to 36 months.”

And while you’re at the store, Breus says we should think of buying two different pillows: one plush and one firm. At the beginning of the week, our body tends to be relaxed, meaning our head and neck need the least amount of support. But after days of work-related stress (and all that staring at our smartphones and computers), our neck muscles tend to be more tense and in need of support. So Breus recommends switching to a firmer pillow on Thursday and Friday nights.