According to a 2017 study, people tend to have more atypical sleep patterns during the hot summer months than during the cold winter ones. That’s because body heat gets trapped in the mattress and blanket. If you try to alleviate this by throwing off the blanket, no heat is retained at all, and you get uncomfortably cold. The solution for many people is to turn up the air conditioning, but that increases energy usage and lowers humidity, potentially causing breathing problems.

Of note is that this isn’t a problem just for the earthbound! Astronauts encounter the same issue when travelling through high-temperature zones. NASA addressed this in the 1980s and developed a revolutionary new type of cooling blanket. Like many of NASA’s innovations, this one made it to the consumer marketplace, and today cooling blankets employing NASA’s technology, and others like it, are easy to find.

Cooling blankets incorporate a variety of approaches to the problem of hot sleeping, and it can be difficult to choose the one that’s best for you. Here’s what to know about cooling blankets and a quick rundown of what’s available.

What Is a Cooling Blanket?

Instead of trapping body heat and creating uncomfortable sleeping conditions like a regular blanket, a cooling blanket allows the heat to pass through its breathable fibers and dissipate. It also wicks up excess moisture, which contributes to cooling because moisture traps heat.

Traditional cooling blankets are made of breathable fabrics, but it didn’t take a rocket scientist to figure out that breathable fabrics are more comfortable for sleeping. The cooling blankets developed by NASA employ Outlast technology. The fabric is embedded with tiny micro capsules called thermocules that absorb body heat when the ambient temperature is high and release it when the temperature drops, thus creating a stable thermal environment for the sleeper.

Cooling blankets can also incorporate an active cooling system in much the same way as an electric blanket provides active heating. Availability of this type of cooling blanket is limited.

Types of Cooling Blankets

Cooling blankets can be made from a number of breathable fabrics, and are often made from a combination for more efficient thermal exchange. The weave is generally looser than a regular blanket, which helps improve thermal exchange. Traditional cooling fabrics include:

• Cotton;
• Polyester;
• Wool;
• Acrylic;
• Bamboo (a fabric derived from bamboo stalks);
• Tencel (the brand name of a fabric made from naturally soft and breathable cellulose fibers);
• Eucalyptus (a super-soft and breathable cellulose fabric manufactured from eucalyptus bark);
• Linen.

Cooling blanket fabric may or may not employ Phase Change Materials (PCMs), the micro capsules developed by NASA as part of its Outlast technology. Along the same lines, 37.5 Technology (37.5 is the ideal body temperature in degrees Celsius) uses naturally sourced volcanic minerals woven into the fabric to regulate temperature.

In addition to breathable fabrics and PCMs, some blankets are weighted with rice, pellets or glass beads, and some are infused with a heat absorbing gel. The final strategy is to equip the blanket with its own tiny air conditioner. A blanket of this type is called an air cooling blanket.