Mattresses Pillows & Bedding ‘Sun washing’ pillows and bedding in a heatwave won’t kill dust mites and fungi — this exact temperature will, infection expert says Features By Claire Davies published 21 June 2026 Dr. Shanina C. Knighton reveals the science-backed temperature for eliminating dust mites, odors and more, and why UV-sanitization is not a replacement for a hot wash When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works . (Image credit: Getty Images) Jump To: How ‘sun washing’ works Why you should air bedding in a heatwave How bedding becomes a ‘moisture bomb’ The washing temperature that actually works How often to wash bedding in summer Copy link Facebook X Reddit Email Share this article 0 Join the conversation Follow us Add us as a preferred source on Google Newsletter Subscribe to our newsletter Each day during a heatwave, my neighbor hangs her pillows and bedding on the line for a few hours of ‘sun washing’ or ‘sun curing’ – a viral cleaning trend that claims leaving bed sheets in direct, super-hot sunlight UV-sanitizes them. I understand the appeal – this ‘CleanTok’ hack is free, and who doesn’t like sleeping in line-fresh bedding? But here’s the microbiological truth: ‘sun washing’ does little to get fungi, bacteria, dust mites and odors out of your pillows, bed sheets and toppers. According to a study on optimal ways to remove dust mites, allergens and pollen, a standard machine wash at 104°F 40°C leaves 94% of dust mites alive and kicking in your bedding. Yep, 94%. So why is my neighbor dead-set on ‘sun washing’ her bedding during a heatwave? “The real benefit is moisture and not disinfection,” says Dr. Shanina C. Knighton, PhD, RN, CIC , an infection prevention expert and Research Associate Professor at the Frances Payne Bolton School of Nursing at Case Western Reserve University. To help us separate cleaning myth from microbiological reality, Dr. Knighton explains what ‘sun washing’ actually achieves, why pillows and bedding become moisture bombs during heatwaves, and the exact temperature a washing machine needs to get rid of the nasties. (Image credit: Getty Images) Key take-aways: At a glance The ‘sun washing’ misconception: Hanging pillows and duvets outside in the sun won’t disinfect them. Sunlight cannot physically lift soil or skin cells, and UV rays can’t penetrate dense pillow and comforter interiors where microbes hide. Why airing bedding in a heatwave is still smart: Moving hot air pulls moisture, sweat, and odors trapped inside dense bedding. It temporarily stops bacteria from multiplying, but it won’t get rid of the bacteria. The wash temperature that works: According to one study, 104°F / 40°C washes leave 94% of dust mites alive in your bedding. To eliminate dust mites and pathogens, you must machine wash your bedding using the warmest setting its care label safely tolerates. The ideal is 130°F to 140°F / 54.4°C to 60°C. When to wash bedding in a heatwave: While pillowcases and bed sheets should be washed once a week (minimum) during summer, step up the frequency if you sweat heavily, skip nighttime showers, have acne-prone skin, or share the bed with pets. Especially during a heatwave. Prioritize a dry bed over a tidy bed: Never make your bed straight after getting up if you’ve been sweating and the sheets felt damp. Pulling up the covers seals in body heat and moisture – the ideal conditions for fungi and odors to multiply during a heatwave. ‘Sun washing’ refreshes bedding — it doesn’t disinfect (Image credit: Shutterstock) With regular use, pillows and bedding house a build-up of fungi, dust mites , other allergens and odors. You may like How to wash your pillows in a washing machine without ruining them ‘More bacteria than a toilet seat’ — study reveals exactly when we need to wash pillowcases and bed sheets for healthier sleep Why does the Apple Watch track wrist temperature while you’re sleeping? We ask Dr. Matt Walker “When researchers at
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