Most of us spend around a third of our lives in bed. Sleep isn't just downtime; it's essential for normal brain function and overall health. And while we often focus on how many hours we're getting, the quality of our sleep environment matters too.

A clean, welcoming bed with crisp sheets, soft pillowcases and fresh blankets not only feels good, it also supports better rest.

But how often should we really be washing our bed linens?

According to a 2022 YouGov poll, just 28 percent of Brits wash their sheets once a week. A surprising number admitted to leaving it much longer, with some stretching to eight weeks or more between washes.

Related: Should You Shower in The Morning or Night? It Depends on One Crucial Factor.

So what's the science-backed guidance?

Let's break down what's actually happening in your bed every night – and why regular washing is more than just a question of cleanliness.

Each night, as we sleep, we shed hundreds of thousands of skin cells, excrete oils from our sebaceous glands, and sweat up to half a pint of fluid – even if we've showered just before bed. Our skin hosts millions of bacteria and fungi, many of which are transferred onto sheets, pillows and duvets as we move during the night.

That fresh sweat may be odorless, but bacteria on our skin, particularly staphylococci, break it down into smelly byproducts. This is often why you wake up with body odor, even if you went to bed clean.

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

Dust mites, fungi and other unseen bedfellows

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

Fungi also find your bed appealing. Some species, like aspergillus fumigatus, have been detected in used bed pillows and can cause serious lung infections, particularly in people with weakened immune systems.

If you sleep with pets, the microbial party gets even livelier. Animals introduce extra hair, dander, dirt and sometimes fecal traces into your sheets and blankets, increasing the frequency at which you should be washing them.

So, how often should you wash your bedding?

Sheets and pillowcases

• When: Weekly, or every three to four days if you've been ill, sweat heavily, or share your bed with pets.
• Why: To remove sweat, oils, microbes, allergens and dead skin cells.
• How: Wash at 60°C or higher with detergent to kill bacteria and dust mites. For deeper sanitization, tumble dry or iron. To target dust mites inside pillows, freeze for at least 8 hours.

Mattresses

• When: Vacuum at least weekly and air the mattress every few days.
• Why: Sweat increases moisture levels, creating a breeding ground for mites.
• Tips: Use a plastic or allergen-proof mattress protector and replace the mattress every seven years to maintain hygiene and support.

Pillow interiors

• When: Every four to six months (check the label first).
• Why: Internal filling can harbor bacteria and mold.
• How: Wash thoroughly and dry completely to avoid fungal growth.

Blankets and duvet covers

• When: Every two weeks, or more often if pets sleep on them.
• Why: They trap skin cells, sweat and allergens.
• How: Wash at 60°C or as high as the care label allows. Some guidance recommends treating these like towels: regular and hot washes keep them hygienic.

Duvets

• When: Every three to four months, depending on usage and whether pets or children share your bed.
• Why: Even with a cover, body oils and mites eventually seep into the filling.
• How: Check the label: many duvets are machine-washable, others may require professional cleaning.

Your bed may look clean – but it's teeming with microbes, allergens, mites and irritants that build up fast. Washing your bedding isn't just about keeping things fresh; it's a matter of health.

Regular laundering removes the biological soup of sweat, skin, dust and microbes, which helps to reduce allergic reactions, prevent infections and keep odors at bay. And as research continues to show the profound effect of sleep on everything from heart health to mental clarity, a hygienic sleep environment is a small but powerful investment in your wellbeing.

So go ahead – strip the bed. Wash those sheets. Freeze your pillows. Your microbes (and your sinuses) will thank you.

Sweet dreams – and happy laundering.

Primrose Freestone, Senior Lecturer in Clinical Microbiology, University of Leicester

This article is republished from The Conversation under a Creative Commons license. Read the original article.