Are Flannel Sheets Warmer Than Cotton Ones?

A fabric and textile expert breaks down the key differences between the two.

Having trouble deciding on the best sheets for your mattress? There are plenty styles and designs on the market, but the material you choose is ultimately the most important factor. Two textiles that get compared quite frequently are cotton and flannel. While they may seem completely different in your eyes (we often associate flannel with winter and cotton with summer), the materials are actually quite similar, and we often field questions on which is warmer. Ahead, we settle the score once and for all with the help of a fabric and textile professional.

Material Difference

When it comes down to it, flannel isn't actually its own fabric type. "Flannel is a type of craftsmanship, whereas cotton is a type of fabric," Travis Zhang, a fabric and textile expert and the senior R&D manager of Bedsure, explains. "A piece of flannel fabric can be made of cotton, wool, polyester, but not vice versa." Most commonly, flannel is made with 100 percent polyester microfiber filament yarn, which is quite different from conventional cotton fabric. "Cotton fabric is made from a plant, so it is a natural fiber," he adds. "Polyester fibers are human-made, synthetic polymers, which are often made from plastic and are widely used in the textile industry. Polyester microfabric is made with very small and thin fibers, which gives the fabric a softer feel than most cotton, which has a crisper feeling." While both materials are durable, polyester tends to be less airy than cotton.

Bed sheet and pillow messed up
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Warmth Factor

So, which material is warmer, exactly? Ultimately, it really depends on the make of the flannel. "Generally, when comparing between the polyester flannel and cotton sheets, yes, flannel sheets are warmer and cozier than cotton ones," Zhang says, adding that they are also softer. The reason? Flannel is made with a soft, woven thread; the fibers are brushed, rendering the material soft against the skin. "The main reason flannel sheets are warmer is because of their fuzzy fibers that help to trap air, creating pockets of warm insulation for the body," he adds. "So, those fuzzy fibers not only feel good, but they also keep people warm. Ultimately, the fuzzier the fabric, the greater the warmth."

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