Everything you need to know about memory foam mattresses. And more.
Science and Memory Foam
As strong proponents of sleep science and science in general, we’ll admit: we’re obsessed with NASA. What science lover wouldn’t be? Many of the world’s most innovative and useful products have been spun off from technologies developed for missions into space. Portable cordless vacuums. Solar panels. Water purifiers. And, importantly for sleep – memory foam, which was actually developed for rocket launches.
Let’s back things up here: in the 1960’s, a contractor at NASA named Charles Yost was tasked with providing better comfort and protection to astronauts during takeoff and reentry. During these two phases, their bodies are under extreme pressure from G forces, so it was crucial to develop a material that would provide enough soft cushioning without disintegrating. While working to solve this problem while subcontracted to NASA in 1966, Yost first developed an entirely new material that he called “Temper Foam.”
It was durable but soft. It had some give but would return to its original form quickly. It was heat-sensitive but thick enough to provide constant padding. Co-inventor Chuck Kubokawa described its effectiveness like this: “We crash-tested several seats at the Civil Aeromedical Institute in Oklahoma City to validate them for impact survival, and we found the foam was good for 36 Gs. The seat can out-survive the aircraft in a crash.” Or, you might say, it had the right stuff.
Memory Foam for the Masses
The appeal of this new material reached far beyond Ames Research Center. In 1980, NASA released the technology, and it has been put to a wide variety of uses ever since: cushioning the helmets of the Dallas Cowboys in the 1960s, providing more comfortable saddles for motorcycles, padding the racecars in NASCAR and Formula 1–even for prosthetics for horses and dogs,
However, it wasn’t until over a decade after NASA released the technology that memory foam made its way into our mattresses. Coil springs were basically the only other option at the time, not counting waterbeds. This new foam material was wholly unlike any existing mattress technology.
So…What Is It?
Memory foam is made from polyurethane (a type of polymer, or large molecule), with certain chemicals added to increase its viscosity and density. The process of making memory foam goes something like this:
- Polyurethane is combined with the chemicals from the family of polyols (alcohols derived from petroleum products or plant oils) and isocyanates (organic amine-derived compounds.
- The mixture is heated and whipped together to produce a foam.
- The foamy mixture is then infused with blowing agents until the air is pumped out, to form an open cell structure.
- The large chunk of foam, at this point referred to as a “bun,” is cooled, then reheated and left to cure. The curing process can be as short as 8 hours and as long as several days.
- The now-inert material is washed, dried, and inspected for any lingering residues.
- Finally, the memory foam is cut into appropriate-sized pieces to be used for mattresses or other products.
- In the case of a mattress, the memory foam pairs up with its counterpart, the pure polyurethane “core” or support layer upon which is rests. Some manufacturers, like Reverie, layer it with latex to let body heat escape.
- A flame-resistant fabric barrier is applied.
It should be noted that as the years have ensued, some manufacturers have upped the game on the manufacturing of memory foam. A few companies, including Reverie, have implemented processes like extra washing to remove toxins and fumes, as well as environmentally friendly practices to reduce the impact on the environment. This premium memory foam often carries the CertiPUR-US® certification.
Density is the key to quality
The density of a memory foam mattress is its primary distinguishing factor, and affects most everything about it.
The denser the foam, the more pressure and heat it requires to give way. More porous foam will yield easily under pressure, even when the force applied is cool. Higher-density mattresses are generally considered higher quality, as they provide more support to your body and spring back more readily. It shouldn’t be a surprise, then, that higher density mattresses also have a longer lifespan, though not nearly as long as latex. (Memory foam gradually disintegrates and reverts to its original form, usually starting within 5-7 years)
The density of memory foam is measured in using ILD (Indentation Load Deflection). This represents the number of pounds of pressure required to indent 4” of foam by 25% using a 50-square-inch indentation.
The inevitable evolution
Memory foam has come a long way since its original incarnation at Ames Research Center in 1966. After NASA released the technology and it began being put to use in the above mentioned products, pragmatic innovators all over began playing with its composition to optimize it for whatever end they chose. In the case of mattresses, this meant adding materials and other chemicals that improved the comfort level of the memory foam.
Most notably among the additives was gel, which made its way into gel visco memory foam, introduced in 2006. This technology fused gel particles with the foam to reduce trapped body heat while also making it spring back more quickly and increasing softness. This particular innovation was developed and patented by Peterson Chemical Technology, and rose to popularity in 2011. Later versions of gel-infused memory foam used beads that would change from solid to liquid within the capsule, which helped further regulate the heat absorption of the mattress.
Today, you might find memory foam mattresses that use a wide variety of innovative materials. Aloe vera, green tea extract, and activated charcoal have been used to reduce odor; rayon and DuPont’s Coolmax® to wick away moisture; we well as polyester, wool, cotton, and many more.
What to Remember about Memory Foam
So what should your lasting impression (ha!) of memory foam be? Is it the right mattress type for you? Well, like much of life, it depends.
All the talk about open-cell structure, moisture-wicking, and trapped body heat should’ve clued you into one of the primary issues with memory foam: it can get hot. A lot of work has been done to mitigate this issue, but many people still find that their memory foam isn’t breathable and “sleeps hot.” If temperature regulation tends to be an issue for you, or you know you’re a hot sleeper, that’s something to consider.
The chemicals used in manufacturing memory foam also pose some issues: on the one hand, the polyurethane makes the mattress combustible; on the other, many of the fire-proofing chemicals used are considered hazardous. Plus, some people notice a distinct and/or strong chemical odor in their mattress, which dissipates over time. Memory foam also tends to be on the more expensive side.
However, memory foam provides a lot of unique benefits. It’s widely used in medical settings and for wheelchair seats, which is a testament to the material’s ability to provide great support without creating any pressure points. The density of the foam, in tandem with its ability to mold to the contours of the body, means that the sensitive, injury-prone parts of your body (hips, knees, neck) are properly cushioned and supported without any painful pressure points.
Not surprisingly, given its NASA applications, memory foam is very effective at absorbing and dissipating force. It also responds differently depending on how the force is applied, yielding less with force that is applied quickly rather than slowly. Which means it’s great at isolating motion. So if you or your partner toss and turn, it’s a good choice.
Currently, some of the best memory foam mattresses are of the hybrid variety, using memory foam for its luxurious feel while combining it with other materials to dissipate heat and increase durability. Ultimately, your mattress choice is highly subjective, and only you know what fits your sleep needs. If, like most of us, you had childhood dreams of being an astronaut, sleeping on memory foam is likely the closest we’ll get.