How often should you wash your sheets? A microbiologist answers.

Most of us spend about a third of our lives in bed. Sleep isn't just a time of rest; it's essential for normal brain function and overall health. And while we often focus on how many hours we sleep , the quality of the environment we sleep in is also important. A clean, cozy bed with fresh sheets, soft pillowcases, and fresh blankets is not only comfortable but also promotes better rest.

But how often should we wash our bedding?

According to a 2022 YouGov survey, only 28% of Britons wash their sheets once a week. A surprising number admitted to leaving them much longer, with some waiting up to eight weeks or more between washes.

Let's take a look at what really happens in our beds every night and why washing them regularly is more than just a matter of hygiene.

Every night, while we sleep, we shed hundreds of thousands of skin cells, excrete oils from our sebaceous glands, and sweat up to half a liter of fluid, even if we showered just before bed. Our skin is home to millions of bacteria and fungi , many of which are transferred to our sheets, pillows, and duvets when we move during the night.

That fresh sweat may be odorless, but the bacteria on our skin, particularly staph, break it down into foul-smelling byproducts. This is often the reason we wake up with body odor, even if we went to bed clean.

But it's not just about microbes. During the day, our hair and bodies accumulate pollutants, dust, pollen, and allergens , which can also be transferred to our bedding. These can trigger allergies, affect breathing, and contribute to poor air quality in the bedroom.

The flakes of skin we shed each night become food for dust mites , microscopic creatures that thrive in warm, damp bedding and mattresses. The mites themselves aren't dangerous, but their droppings are potent allergens that can aggravate eczema, asthma, and allergic rhinitis.

Fungi also find your bed attractive. Some species, such as Aspergillus fumigatus, have been detected in used pillows and can cause serious lung infections, especially in people with weakened immune systems.

If you sleep with pets, the microbial party gets even more lively . Animals introduce hair, dander, dirt, and sometimes fecal matter into sheets and blankets, increasing the frequency with which we need to clean them.

So how often do we have to wash our bedding?

When: Weekly, or every three or four days if we've been sick, sweated a lot, or shared a bed with pets.

Why: To remove sweat, oils, microbes, allergens, and dead skin cells.

How to: Ideally, wash them at 60°C or higher with detergent to eliminate bacteria and dust mites. For deeper disinfection, you should tumble dry or iron them. To eliminate dust mites from the inside of your pillows, you can freeze them for at least 8 hours.

When: Vacuum at least once a week and air the mattress every few days.

Why: Sweat increases humidity levels, creating a breeding ground for mites.

Tips: Use a plastic or hypoallergenic mattress protector and replace your mattress every seven years to maintain hygiene and firmness.

When: Every four to six months (check the label first).

Why: The inner filling can harbor bacteria and mold.

How to: Wash them thoroughly and dry them completely to prevent the growth of fungus.

When: Every two weeks, or more often if pets sleep on them.

Why: They trap skin cells, sweat, and allergens.

How to: Wash them at 60°C or the maximum temperature indicated on the label. Some recommendations advise treating them like towels: regular, high-temperature washes keep them hygienic.

When: Every three or four months, depending on use and whether pets or children share the bed.

Why: Even with a cover, body oils and dust mites eventually penetrate the filling.

How to: Check the label: Many comforters are machine washable, others may require professional cleaning.

Our beds may look clean, but they're filled with microbes, allergens, mites, and irritants that quickly accumulate. Washing your bedding isn't just a matter of hygiene, but also of health.

Regular washing removes the biological mix of sweat, skin, dust, and microorganisms, helping to reduce allergic reactions, prevent infections, and keep odors at bay. And, as research continues to show, sleep has a profound effect on everything from heart health to mental clarity, so a hygienic sleeping environment is a small but powerful investment in your well-being.

So go ahead: unmake the bed. Wash the sheets. Freeze the pillows.

Sweet dreams and happy washing.

This article was originally published on The Conversation .