Like clockwork, every night we slip into our sleepwear and drift off into a slumber. Pajamas act as a barrier between our bodies and bed sheets to keep us warm, but a new survey suggests we may be better off sleeping naked. According to the poll conducted by Ergoflex, a memory-foam mattress company, not washing your pajamas for over a week may leave you susceptible to developing MRSA, cystitis, and skin infections.

“Pyjamas are against your skin. You shed skin cells at a vast rate all the time. They are full of microorganisms. We all have skin and gut organisms that are usually not harmful on our skin and in our gut. But if they get into the wrong place, they can cause problems. Quite a lot of us carry staphylococcus bacteria, which can cause infections if they get into cuts and bruises,” said Professor Sally Bloomfield from the London School of Hygiene & Tropical Medicine, after viewing the results, the Ergoflex blog reported.

The poll analyzed nearly 2,500 British couples aged between 18 and 30 years old on their sleepwear and bedtime hygiene habits. The most popular choices among women were the traditional “two-piece pajama set” at 37 percent, “underwear only” at 28 percent, and “partner's nightwear” at 26 percent. Similarly, the popular choices among men were “underwear only” at 38 percent, “pajama pants/shorts” at 35 percent, and “two-piece pajama set” at 19 percent. Although these couples went to bed in pajamas, 19 percent of couples admitted to waking up wearing far less clothes, with socks and tops as the most commonly removed items at 31 and 14 percent, respectively.

The survey participants also blatantly admitted they wash their preferred sleepwear infrequently. When it comes to bedtime hygiene, women are found to be the grosser sex. Men wear their pajamas for an average of 13 nights before washing them, while women go even further and wear the same pair for an average of 17 nights. Excuses for infrequent washing for 64 percent of women were that by alternating between multiple pairs, it’s easy to forget how long they’ve been out for. Meanwhile, over two-thirds of men claimed they didn’t do the washing and just wore what was available. About half of both men and women claimed since their pajamas didn’t smell to them, they didn’t see the problem with irregular washing.

Although men may be the better sex when it comes to pajama hygiene, they fall short in changing the sheets. A previous Ergoflex survey of 18- to 25-year-old single men found more than half reportedly change their bed sheets on average every three months. Women, however, maintained good hygiene in this scenario, with about two-thirds aged 35 to 50, changing their sheets on average every week.

It seems while men are better at swapping their pajamas, and women swapping bed sheets, it could all be useless if one or the other is not regularly washed. Changing out of your pajamas could lead to the transfer of the microbes on to other clothing. Pajamas can get heavily contaminated with microbes and will most likely be transferred to other linen in the washing machine.

Washing gets rid of most microbes, but not if you have worn your pajamas for two weeks. “The clothes won’t be hygienically cleaned because the microbes will have built up,” Bloomfield said. “So they will be transferred to underwear and other clothing that comes into contact with the skin.”

Practicing good bedtime hygiene is extremely vital, especially since we all carry the E. Coli bacteria in our bowl. Although most strains aren’t harmful, says Bloomfield, they can cause an infection if they get into the urinary tract. “That would cause cystitis (a urinary tract infection). Some people carry MRSA, which obviously gets very hard to treat, especially with antibiotic resistance,” he said.

Bed linen and pajamas worn for a long period of time are subjected to a similar fate. Even if bedding is washed regularly, if it comes in contact with unwashed sleepwear it won’t stay fresh for too long. Bloomfield recommends washing your pajamas after a minimum of a week's use, or after three to four wears, according to the American Cleaning Institute. If you shower before bed, you may get a few more wears before washing. Unlike pajamas, bed sheets should be washed at least every two weeks, or more often if you sweat a lot.

Keep both your bed sheets and sleepwear clean to promote a hygienic and healthy sleeping environment, and most importantly, to get a good night’s sleep.