How often you should wash them: After 3 to 4 wears.
What to know: Swap out your pj’s twice as often as you change the sheets. “People don’t realize how much they sweat at night,” says Elizabeth Scott, Ph.D., a codirector of the Simmons Center for Hygiene and Health at Simmons College, in Boston. “We also shed thousands of skin cells a minute.”
Exception to the rule: Do you shower before bedtime? If the answer is yes, you can sneak in an extra wear or two. However, if you snooze in silk, which absorbs more body oils than cotton, you should switch up your sleepwear daily.