Every summer, the internet gets fascinated by hacks to stay cool, and “cooling blankets” often top the list. The claims sound amazing—blankets that keep you chilled even on hot, humid nights. But are these products the real deal, or just marketing hype? Let's see what the science has to say.
What Does Temperature Actually Mean?
We often talk about something being 'hot' or 'cold,' but temperature is really about the average kinetic energy of molecules—their motion and vibration. When two objects touch, heat flows from the warmer to the cooler one until they reach the same temperature. Heat goes from hot to cold, never the other way around.
Do Blankets Really Cool or Just Insulate?
Blankets are fundamentally insulators—they slow down how quickly your body loses heat to the environment. In winter, this keeps you warm. If it's already hot, wrapping up in a blanket traps body heat and keeps you even hotter unless the blanket itself is cooler than you. The only way a blanket cools you is if it starts off colder than your body, like if you took one out of a cold room or freezer. You'll feel cool for a few minutes, but soon your body heat warms the blanket and you're back at square one.
Why Do Some Materials Feel Colder?
Here's a classic experiment: pick up both a wooden block and an aluminum block at room temperature. The metal feels much colder because it takes heat from your hand much more quickly (it's a better conductor). The same thing explains why swimming in water at 75°F feels colder than air of the same temperature—water carries heat away from your body faster.
Are “Cooling Blankets” Any Different?
Most “cooling blankets” you see online are really just lightweight, breathable fabrics that don’t keep heat in as much as regular blankets. They won’t make you cooler than being uncovered; at best, they just don’t make you hotter. Tests with infrared cameras show little difference—they’re all just blankets at room temperature.
The Science Behind Real Cooling Blankets
But could a blanket actually keep you cool for more than a few minutes? Enter phase-change materials (PCMs). These substances absorb a lot of heat as they melt but stay at the same temperature—for example, ice at 32°F absorbs heat until fully melted without getting warmer. If you use a PCM that melts just below skin temperature (around 65°F), a blanket with PCM packs could absorb excess body heat for hours, not just minutes, keeping you genuinely cool.
Homemade PCMs, like carefully chosen salt solutions, can melt just below body temperature, providing hours of sustained cooling. Once the material has fully melted and absorbed as much heat as it can, you “reset” it by putting the blanket back in a cool place or a refrigerator.
Want to see this concept in practice? Check out this demonstration:
https://youtu.be/Nqxjfp4Gi0k?si=5pUBJUcsUhT1a0CI
The Takeaway: Science Over Social Hype
Most “cooling blankets” just trap less heat than regular ones and don’t make you cooler than using no blanket at all. If you want true cooling, look for products with phase-change materials at human-tolerable melting points. Otherwise, you’re better off ditching the blanket—or at least treating the wild online claims with skepticism.
Source: https://www.wired.com/story/are-those-viral-cooling-blankets-for-real/