The next time you get into your boyfriend’s bed, you might want to rethink what’s about to happen. According to a survey by the U.K. mattress company Ergoflex, single British men wash or change their bed sheets, on average, only four times a year.

“We were quite alarmed at the apparent lack of basic hygiene from some respondents,” Jed MacEwan, a spokesman for Ergoflex, told the Daily Mail. Out of single men, ages 18 to 25, 55 percent reported changing their sheets an average of every three months. Even worse, 49 percent reported being okay with only cleaning them four times a year, and 19 percent simply didn’t care about it. The women they slept with did, however, because 17 percent of respondents also said that romantic partners had been “put off” by their soiled sheets, according to CBC News. Of the 2,004 people surveyed, the average man owned only one set of bed sheets, while the average woman owned three.

Women, on the other hand, were much cleaner, reporting that their bed sheets were changed an average of every 2.5 weeks. Couples also slept on clean sheets, changing them every two weeks. But most of the credit can go to the women, since they were the ones changing them 80 percent of the time. Age was also a factor, with those between the ages of 35 and 50 more likely to change their sheets every week, Time reported.

“Romantic ambitions aside, we were more alarmed by the potential health risks that unhygienic bed-sheets could cause, considering in particular two unwelcome nighttime companions — dust mites and bedbugs,” Steven Willis, of Ergoflex, wrote in a blog post.

As humans sleep, they “perspire as much as a liter a night — even more if you have a lot of covers,” Philip Tierno Jr., director of clinical microbiology and immunology at NYU’s Langone Medical Center, told the Wall Street Journal. He says that skin cells can provide a source of food for mites, leading them to populate sheets even more. Bedbugs, perhaps, are an even worse issue. The small parasitic insect feeds on people’s blood while they sleep and can cause bite marks to appear, as well as itchiness or an allergic reaction. But washing sheets, linens, and clothing in hot water and drying them on the highest temperature setting could kill them.

“Avoiding regular cleaning of bed sheets helps create an undisturbed habitat for bedbugs, and positively encourages their presence,” Willis wrote. “We wonder if those respondents in our survey who claimed they ‘didn’t see the need’ to regularly wash their sheets would feel the same way if they knew what a veritable micro-zoo they were cultivating in their grubby beds!”

Willis also compiled a list of interesting comments about the survey, here were a few:

· We have to wash our sheets?

· Three months? That often?

· I’m a single guy, change mine every week, and like keeping the place clean and tidy. Also, I have a good job, and can do the washing up. Apply within.

· After about six months, or when I start sticking to them, I usually sprinkle some talcum, powder on my sheets to freshen them up. Works a treat.