Can you imagine Beth the first time laying on Howard's cum incrusted sheets. If you’re a single man, you may go to bed with a clear conscience but you rarely sleep on clean sheets. At least, that’s according to a new study, which found that single men on average only clean their bed sheets four times a year. In comparison, single women change their bed sheets every two weeks. And while cleanliness numbers surge for married couples, it appears the credit for the median boost for guys primarily belongs to women. In fact, it may be the men who are dragging the women down, as the average washing frequency amongst couples is once every 2.3 weeks, with women doing 81 percent of the washing. And as “How Stuff Works” points out, the average person spends about a third of their entire life in bed. In other words, the old saying, “ As you make your bed, so you must lie on it,” may have more meaning than originally intended. But are these single men literally sleeping in beds of filth? Or, are the women perhaps overdoing it a bit? Turns out, it mostly depends on your own standards of cleanliness. For example, Martha Stewart recommends washing the sheets weekly, but notes that itultimately is an issue of personal preference. The Wall Street Journal also says that weekly washes are the norm but that many other go several weeks between cleanings. For people with asthma or other allergies, clean bed sheets are more of a priority. That’s because sheets, and mattresses and pillowcases in particular, are excellent at accumulating dust and microorganisms that can disrupt otherwise healthy breathing patterns. In that case, many experts recommend laying plastic covers on top of mattresses and even pillows in order to keep those microorganisms from making a home inside the mattress or pillow padding. "The conventional idea is that you might exacerbate eczema, hayfever or asthma at night, but all of these ideas are more based on conventional wisdom, not necessarily founded in experience," Euan Tovey, head of the Allergen Research Group at the Woolcock Institute of Medical Research told MSN. "We've done research that showed that you don't get as much exposure to dust mites in bed as we once thought. Anywhere where there is dust and movement you are going to get exposure –– it's not confined to bed," he added. According to the survey, people between the ages of 35 and 50 are the most likely to wash their bed sheets each week. So, as Tovey said, health concerns might not be a major issues for younger sleepers. But it certainly could be an aesthetic one for younger men hoping to forge meaningful romantic relationships. "Would you want to be invited into a bed of somebody who hadn't washed it for months?" Tovey said.In news that is hardly surprising, a UK survey has found most single men only change their sheets every three months.That's compared to single women who change their linen every two weeks.Guys aged 18 to 25 are the worst offenders, with more than half of those surveyed admitting to only washing their sheets four times a year.More than 20 percent of them said they "didn't see the need" to change the sheets more and 19 percent said they "didn't care" about changing them more.Couples in relationships change their bed linen every 2.3 weeks, however that's not because men suddenly become more hygienic –– women reportedly are the sheet-changers in 81 percent of couples.People aged between 35 and 50 are most likely to change their sheets weekly, the survey found.Associate Professor Euan Tovey, the head of the Allergen Research Group at the Woolcock Institute of Medical Research, told MSN that while washing sheets removes dust mites and other allergens, it isn’t a serious health concern."The conventional idea is that you might exacerbate eczema, hayfever or asthma at night, but all of these ideas are more based on conventional wisdom, not necessarily founded in experience," he said."We've done research that showed that you don't get as much exposure to dust mites in bed as we once thought. Anywhere where there is dust and movement you are going to get exposure –– it's not confined to bed."If you find yourself wheezing or sniffling in bed or developing a skin irritation, Associate Professor Tovey said you probably need to alter your sleep hygiene conditions.He said the more serious risk is probably to your reputation."Would you want to be invited into a bed of somebody who hadn't washed it for months?" he asked."I think it's more of an aesthetic thing than a health thing."Dr Maree Barnes, from the Sleep Health Foundation, said dirty sheets are unlikely to impact your sleep quality if you're not particularly fussed about personal hygiene."Everybody has different needs for getting a good night's sleep," she said."For some people it's important to change their sheets often and have high thread count sheets. It would impact on my sleep because I don't like smelly uncomfortable sheets, but I don't know that young men really care or notice it."