Why you might want to change your bedclothes more often
Our sheets and pillows are where we spend a third of our daily lives, and all that contact creates the perfect environment for all sorts of unwanted guests.
After a long day, there's nothing quite like the feeling of sinking into a warm bed, resting your head on a soft pillow and cocooning yourself within a cosy duvet. It isn't just us humans though that find lying in a bed blissful, however.
Look beneath the surface and you may be horrified to learn that your bed linen is host to millions of bacteria, fungi, mites and viruses. Each of them thinks that your bed is heaven too; a warm place that they can grow in, full of sweat, saliva, dead skin cells and food particles to feast on.
Take dust mites. We shed 500 million skin cells a day, which if you are a tiny dust mite is like an all-you-can-eat buffet. Unfortunately, both the bugs and their droppings can trigger allergies, asthma and eczema.
Bed sheets are a haven for bacteria too. For example, in 2013, researchers at the Institut Pasteur de Lille in France analysed the bed linen of hospital patients and found that dirty sheets were brimming with Staphylococcus bacteria, a bacteria commonly found on human skin. Although most species of staphylococcus are benign, some, such as S. aureus, can cause skin infections, acne and even pneumonia in patients with weakened immune systems.
"People carry bacteria as part of their skin microbiome and can shed them in large numbers," says Manal Mohammed, a microbiologist at the University of Westminster in the UK, who was not involved in the study.
Hospitals wash sheets at very high temperatures to try and kill as many microbes as possible (Credit: Getty Images)
"Although these bacteria are typically harmless, they can cause serious illness if they enter the body through open wounds, which are more common in hospitals," Mohammed says.
Hospitals are a rich source for data because hygiene is taken seriously, and bedclothes and pillows are washed between patients. In 2018, scientists at the University of Ibadan in Nigeria found E. coli in unwashed hospital bed clothes, along with other pathogenic bacteria known to cause urinary tract infections, pneumonia, diarrhoea, meningitis and sepsis.
Unclean linen represents a real infection risk in such settings. In 2022, researchers collected samples from the rooms of patients hospitalised with monkeypox (now called mpox). They found that the act of changing bed linen released viral particles into the air. In 2018, a UK healthcare worker was thought to have developed the disease after being exposed to the virus while changing a patient's bedding.
At least in developed countries, hospitals have had to institute rigorous procedures to limit transmission.
"In hospitals, they wash linen at very high temperatures, which kills most of the bacteria," says David Denning, professor of infectious diseases and global health at the University of Manchester in the UK.
The exception is C. difficile, a bacterium which causes diarrhoea, especially in older people. According to Denning, washing sheets can destroy up to half of C. difficile bacteria, but the bacterium's spores are hard to kill. Even so, infection rates of C. difficile have gone down in the UK, suggesting that standard hospital laundry procedures, as long as they are followed, are enough to keep the risk of transmission very low.
Of course, you are more likely to find pathogenic bacteria in hospital linen where sick patients have been sleeping than in the bed clothes of healthy people. But what about your run-of-the-mill pillows and bed sheets at home? In 2013, American bed company Amerisleep claimed they took swabs from a pillowcase that hadn't been washed in a week. The pillowcase contained around three million bacteria per square inch – about 17,000 times more than the average toilet seat.
