What is Memory Foam? The Complete Guide to Different Types of Foam Mattresses

What is Memory Foam_

After Heinrich Westphal invented the innerspring bed during the late 1800s, the mattress didn’t change much for more than 100 years.

But in 1992, the sleep industry took a giant leap forward. Tempur-Pedic, a Swedish mattress manufacturer, released a bed made from an innovative viscoelastic polyurethane foam material engineered by NASA for aircraft-seat cushioning. Viscoelastic polyurethane or “memory foam” conforms to the shape of the body when heat and pressure is applied, thus delivering exceptional comfort, pressure relief, and support.

More than 25 years after its introduction to the sleep world, the memory foam mattress continues to be loved and evolved. But conventional memory foam is by no means the only type of foam bed on the market. Today, you can find many different kinds of memory foams -- such as gel and open-cell memory foam -- in addition to mattresses made from other foams like polyfoams and latex foams.

Although classic and enhanced memory foams, polyfoams, and latex foams share similarities, these different materials each come with distinct benefits and drawbacks. We’ve created a complete guide to foam beds to help you understand each material and determine the best bed for you.

Memory Foam

Memory foam, also called viscoelastic foam, didn’t begin as a mattress material. In fact, in was developed by NASA scientists to help cushion astronauts during space shuttle launches. Since being released for commercial use, however, memory foam has been embraced by mattress manufacturers, who have tweaked and enhanced the material over the years.

So what is memory foam, exactly? Memory foam is manufactured similarly to polyfoam, using a complex chemical reaction that was discovered in the 1950s. Memory foam follows the same basic process for creating polyfoam, but includes additional agents that increases its density and viscosity.

With its unique construction, memory foam responds to heat and pressure differently than other types of surfaces. Memory foam conforms to the weight and temperature without exerting pressure in return. A memory foam mattress contours the sleeper’s curves, regaining shape once heat and pressure are removed.

 

 

Thanks to its chemical makeup and design, memory foam is able to deliver superior pressure relief and support. The material supports your body along its natural curves, helping to relieve joint pain and keep your spine in healthy alignment. Memory foam also offers above-average motion isolation, keeping your movements from transferring across the bed to disrupt a sleeping partner.

On the other hand, there are a number of issues associated with traditional memory foam. Many sleepers find conventional memory foam mattresses retain heat, resulting in “sleeping hot” or overheating during the night. Others find that the slow response of traditional memory foam restricts motion and leads to the feeling of being “stuck” in bed.

Pros:

  • Relieves pressure points
  • Decreases stress on your joints
  • Supports your spine’s natural alignment
  • Prevents motion transfer
  • Many different brands and price ranges

Cons:

  • Some sleepers find it leads to overheating, aka “sleeping hot”
  • Lower-quality memory foam is prone to sagging
  • Slow response can make it difficult to shift positions and lead to the feeling of being “trapped” in bed
  • May come with an initial new mattress smell or “off gassing” odor
  • Little to no bounce

To address some of the drawbacks associated with traditional memory foam, many manufacturers have since adapted and enhanced the original structure. Today, you can find a variety of new memory foams engineered with technologies to keep you cool, promote freedom of movement, and provide other benefits. Some of the most common types of new and infused memory foam materials on the mattress market include:

  • Open-cell memory foam. While conventional memory foam uses a close-cell manufacturing process, open-cell memory foam is injected with miniscule air pockets. The less dense, open-cell design allows a quicker response time and promotes breathability, helping you to sleep cool.  
  • Gel memory foam. Introduced to the market around 2011, gel-infused memory foam is designed to help regulate sleep temperature. Gel memory foam beds are made with the addition of a liquid cooling gel, typically by mixing gel microbeads into the memory foam material. The gel beads can help wick away heat and keep you cooler than a traditional memory foam bed.
  • Copper-infused memory foam. Embraced since ancient times as an alternative medicine, copper is a unique element that offers some interesting benefits. Copper is naturally cooling and antimicrobial, and believed to help reduce joint inflammation and enhance blood circulation. Recently, select mattress manufacturers have integrated copper into their foam beds to harness cooling and other benefits.

Polyfoam

Polyurethane foam, aka polyfoam, is the most commonly used mattress material. It’s similar in structure to memory foam, but missing the chemical agents that provide memory foam’s additional density and viscosity. The slight differences in makeup generally make polyfoam less expensive, but also less dense, less durable, and not as conforming.  

Engineers can manipulate the structure of polyfoam during the manufacturing process to add or decrease density and rigidity.  Mattress companies often use low-density polyfoam in the top comfort layers of mattresses to create a softer feel, and denser or high-grade polyfoams in the core and foundation of bed to provide support.

Pros:

  • Inexpensive
  • Widely available
  • Sleeps cooler than conventional memory foam

Cons:

  • Shorter lifespan compared to other mattress materials
  • May not conform as well as memory foam

Latex Foam

Latex foam is distinctive from memory foam and polyfoam in both construction and feel. Latex mattresses are made from natural or synthetic rubber, or a blend of the two. Harvested from rubber trees, natural latex is considered to be one of the most earth-friendly and sustainable mattress materials. Synthetic latex, on the other hand, is constructed from petroleum-based ingredients and other agents.

Both natural and synthetic latex beds are manufactured through one of two processes: the Dunlop or Talalay method. The Dunlop method involves whipping liquid latex with chemicals, then molding and curing the latex with heat.The Talalay process adds two extra steps to this process, using a vacuum to remove air pockets and then flash-freezing the latex.

The extra steps in the Talalay manufacturing process make the latex less dense and bouncier. The process of making Talalay latex beds also typically consumes more energy to manufacture and results in a higher price point than Dunlop beds.

Compared to other foams, latex generally sleeps lighter and cooler. While memory foam sinks and hugs, latex tends to compress and bounce. With a latex bed, you may notice more of a floating sensation as opposed to a sinking feeling.

Pros:

  • Natural latex is eco-friendly, sustainable, and hypoallergenic
  • Long lifespan, particularly for natural latex
  • May sleep cooler than memory foam beds
  • Bouncy and responsive, allowing for freedom of movement

Cons:

  • Heavy
  • Often more expensive than other types of mattress materials

 

 

Comparing the Densities of Different Foam Beds

In addition to other distinctions, the different types of foam beds feature varying density levels. Mattress density affects the quality and longevity of a bed. Speaking generally, mattresses with higher densities are more solid and durable. Mattresses with lower densities, on the other hand, are lighter and have a shorter lifespan.

In the U.S., mattress density is typically indicated in pounds per cubic foot (PCF). For example, with a mattress with a density of 3 PCF, each cubic foot of a mattress will weigh four pounds.

Let’s take a look at the different average densities associated with different types of mattress materials:

  • Memory foam. Whether you’re shopping for a traditional memory foam or infused memory foam bed, you’ll generally want to look for a density of around 4 to 5 PCF. A bed with less than 3 PCF will typically have a shorter lifespan, while one with over 5 PCF could be excessively firm.
  • Polyfoam. Your average polyfoam-based mattress will have a density of around 1.8 PCF, though higher quality, longer-lasting polyfoams may exceed 2.5 PCF. As a general rule, higher-density polyfoams will maintain their support and bounce over a longer period of time.
  • Latex. Today, latex mattresses typically range in density from 3.75 PCF to 5.93 PCF. A low-density latex is typically less durable and softer, while high-density latex is more durable and firmer.
Material Low Density Medium Density High Density
Memory Foam < 4 PCF 4 to 5 PCF > 5 PCF
Polyfoam < 1.5 PCF 1.5 to 1.8 PCF > 1.8 PCF
Latex < 4.3 PCF 4.3 to 5.3 PCF > 5.3 PCF

A note about mattress density versus firmness: Although often correlated, mattress density and mattress firmness are not the same thing. Mattress firmness is indicated by indentation load deflection (ILD), a measurement of how many pounds of force it takes to indent a foam to 25 percent of its original height. The higher the ILD, the firmer the mattress.

In memory foam and polyfoam beds, density and ILD are separate measurements. In latex foam mattresses, however, density and firmness are almost always directly corresponding -- e.g. a high-density latex mattress will usually have a high ILD rating.

How to Choose the Right Foam Mattress for You

Ultimately, memory foam, polyfoam, and latex foams each come with their share of perks and pitfalls. Choosing the best foam bed for you comes down to personal preferences, needs, and budgets. We’ve outlined some suggestions from our editors for choosing a foam bed below.

Choose memory foam if…

Contouring and pressure relief are your main priorities. Memory foam is ideal for sleepers who crave the sensation of being hugged by the mattress or sinking into bed.

If you tend to sleep hot, consider an infused or open-cell memory foam. The enhanced designs of these memory foam spin-offs allow you to sleep cool while enjoying the pressure-relief and contouring benefits of classic memory foam.

Choose polyfoam if…

Budget is your main concern. There is a huge variety of polyfoam beds on the market today, meaning you’ll be able to find a decent bed at a low price with a bit of digging. When shopping for a polyfoam-based mattress, look for a bed with a higher density to ensure optimal longevity.

Choose latex foam if…

You’re after bounce, reponsivness, cooling, and durability. Go for a natural latex bed if sleeping green and healthy are among your top criterias.

Final tip: when shopping for a foam bed, keep your body weight in mind. If you are a heavier sleeper, you may want to choose a denser mattress for a bit of extra support and durability. Lighter sleepers, on the other hand, may need a mattress with less dense layers on the top to avoid excessive firmness.