How often do you change your bedsheets? According to scientists, if you’re changing them less than once a week you’re unwittingly spending your nights in a “botanical park” of bacteria and fungus.

New York University microbiologist Philip Tierno told Business Insider that our beds can build-up a “significant” amount of bacteria in as little as seven days.

Between those bedsheets it’s a hive of invisible fungi and bacteria activity, with lots of microbes from our sweat, sputum, skin cells and vaginal and anal excretions. Nice!

Hot weather: bacteria breeding ground

The problem gets even worse during hot weather. Every year in bed we naturally produce around 26 gallons of sweat and moist, warm conditions make a perfect environment for fungal growth.

It’s not just our own microbes we’re sleeping in, either. Our beds are contaminated by all sorts of foreign bodies like animal dander, pollen, soil, lint, dust mite debris and faeces.

And as we spend so much time with our mouths and noses pressed against our bedding, unclean sheets can trigger annoying symptoms such as sneezing or a scratchy throat.

“Even if you don’t have allergies per se, you can have an allergic response,” Tierno said.

change your bedsheets

Here’s another fun fact from the microbiologist: our mobile phones, those things we carry everywhere, are teeming with microbial life. They collect bacteria and viruses like E. coli and MRSA from our skin, respiratory tract, and other unmentionable body parts. So! Yeah. While you’re changing your sheets, you might want to give your phone a quick clean as well.

The feel good factor

Too many microscopic nasties are bad for everyone, but particularly those who already have respiratory issues like asthma.

Bacteria build-ups can also cause breakouts, so if you have spot-prone or sensitive skin, washing your sheets and wiping your phone more often will do you a big favour. You might even want to change your pillow cases a few times a week, just to be sure.

Clearly there’s a lot of good reasons to change your bedsheets regularly. And here’s one more: getting into clean sheets just feels so good. It’s probably the real reason why some people bother to change their sheets at all. That new-bedding feeling – ah! – is well worth the short time it takes to strip and make a bed.