Sleep specialists consistently note that a cooler sleep setting helps people drift off and remain asleep. Body temperature naturally lowers during rest, a cycle that begins about 2 hours before bedtime, encourages melatonin production, and signals the brain that it is time to sleep. When the sleep environment gets too warm, core temperature can be disrupted, leading to restlessness, reduced sleep quality, and less restorative sleep.

Engineering fabric that pulls body heat away from the sleeper

Fabric cooling is evaluated with Q-Max, a physical measurement that reflects the instant sensation of “coolness” when skin meets a surface. For comparison, silk measured 0.19 W/cm² while cotton sheets measured 0.11, with higher values feeling cooler to the touch. In our Comparative Cooling Experiment, proprietary Evercool® fabric reached a Q-Max rating of 0.40 — twice as cool as silk and nearly 4x that of cotton. This creates an immediate refreshing effect that supports the body’s natural temperature drop for sleep.

The body continues producing heat even during sleep, and traditional bedding such as cotton often behaves like insulation, holding that heat in and causing night-time wakeups. To address this, our R&D team moved beyond conventional textiles into heat-transfer science and high-thermal-conductivity polymers.

Through advanced materials and thermodynamics, we developed bedding that can feel like the “cool side of the pillow” throughout the night. The second law of thermodynamics states that heat naturally moves from hot to cold; Evercool® fabric amplifies that principle with a highly conductive polyamide yarn. In practice, Rest built a textile that moves heat away from the body faster than silk, bamboo, or cotton, helping hot sleepers stay cooler and more comfortable.

We improved the cooling effect of our sheets even further by knitting silver yarn together with Evercool® fibers. Silver is among the most conductive elements on earth at 429 W/(m·K), roughly 1,700 times more conductive than common synthetic fibers such as polyester.

The end result is a fabric that does more than simply “feel” cool; it functions as a heat sink, actively drawing extra heat away from the body so it can dissipate.

A performance textile engineered unlike ordinary fabric

Several fibers then become yarn. Most textile yarns are produced with a method called Drawn Textured Yarn, which appears crimped and irregular under a microscope. That type of yarn can look and feel rough, with weaker smoothness and heat-transfer performance. Although it is more technically demanding, Rest uses Fully Drawn Yarn (FDY), an advanced process that forms straight, consistent yarns with a round cross section.

Our yarn specification is 80D/68F, meaning 68 individual microscopic fibers form a single strand of yarn with an 80 denier diameter, about the same thickness as human hair. These yarns are then processed on a rare, specialized machine that knits them into a dense fabric that is durable and machine washable while still feeling delicate.

Creating fabric that manages moisture for uninterrupted rest

Overheating is one of the main reasons people wake during the night as the body lowers its core temperature for sleep. The body sweats when it gets hot to help cool itself down, but that same sweat can interrupt sleep. Rest addressed both concerns by developing a specialized textile that stays cool while also moving perspiration away for more continuous rest.

Bedding can be an ideal environment for micro-organisms that thrive on warmth, moisture, and bodily buildup such as dead skin cells. To deliver more complete comfort, we created the world’s first truly antimicrobial bedding.

A sleep surface designed to stay cleaner between washes

With IONIC+™ technology, Evercool®+ bedding naturally and actively kills microbes to preserve hygiene between washes. Silver yarn containing positively charged ions is knitted directly into the fabric, remaining permanently antimicrobial unlike chemical coatings or sprays that can wash away.