Washing sheets isn’t exactly the easiest chore around — but it’s necessary, nonetheless.

How often do you wash your sheets? Once a week? Once a month? Well, according to Phillip Tierno, a microbiologist and pathologist at the New York University School of Medicine, it should be on average once a week.

Why? Beds accumulate all sorts of things while we sleep from skin cells to cosmetics. Don’t forget about sweat, especially in the warmer months.

“Gravity brings down all this debris and it settles in the core of the pillow and the mattress. And you’re inhaling that debris 8 hours a day,” Tierno told Tech Insider.

The debris accumulates in the short time span of one to two weeks, hence the frequent washing recommendation. Not only is this debris in your bed bad for your health (and gross), but it also becomes a hotbed for microscopic life.

With that fact alone, we’ve added laundering our sheets to our weekly to-do list. What about you?

xx, The FabFitFun Team