Mattress Guides

What Is Memory Foam?

We have the lowdown on this popular mattress material.

By Alex Reale

Memory Foam: A Brief History

Memory foam is technically known as ‘viscoelastic foam’ and was developed by NASA in the late 1960s. NASA’s researchers originally created the material for use in seat belts and harnesses; the idea was that the foam could improve seat cushioning and create greater crash protection for pilots and passengers.

The name ‘memory foam’ arose from the product’s signature feel, which conforms closely when pressure is applied and springs back very slowly when pressure is released, effectively “remembering” the impression of a hand, body or object.

Not long after its creation, many industries realized the material’s potential for commercial application. The mattress industry was among the first early-integrators of memory foam and mattresses remain the leading use for memory foam today. To create memory foam, polyurethane is combined with chemicals, resulting in the viscous, fluffy, slow-release material that many sleepers love.

What is Memory Foam Made of?

Memory foam is made primarily from polyurethane but also contains additional chemicals that increase its density, elasticity and viscosity. All memory foam starts the production process as simple polyurethane foam, which is created by combining water, halocarbons, and hydrocarbons to a polyurethane mix.

To produce modern memory foam, polyol is mixed with diisocyanate and water. This causes the foam to rise, creating an open-cell structure that gives memory foam its unique ability to spring back slowly from pressure.

Next, gases are introduced to create a bubble. Various chemicals can be added to change the size of the bubble. An open-cell structure memory foam will have more give and airflow throughout. The density, or ILD, of the memory foam can be altered as well. 

What are the Different Types of Memory Foam?

There are four main types of memory foam, which include traditional foam, gel foam, plant-based foam, and copper-infused foam.

  • Traditional—Traditional memory foam was introduced commercially in the ‘90s and has been in use for decades. It has an open-cell structure, which reacts to heat and pressure to contour to the body and alleviate pressure points.
  • Gel—Because memory foam is known for trapping heat, gel memory foam was introduced to help the product disperse heat. Most people who sleep hot can find comfort on memory foam mattresses that contain one or more layers of gel-infused foam.
  • Plant-Based—To create plant-based memory foam, a large portion of the petroleum used to create traditional memory foam is replaced with plant-based oils. This allows consumers to experience increased breathability and is more eco-friendly in nature.
  • Copper-Infused—In this newer take on memory foam, copper-infused versions use beads lined with copper wire to help you sleep cooler by conducting energy away from the body. This type may also promote healthier blood circulation.

How Does Memory Foam Work?

Memory foam is designed to soften and mold around a sleeper’s body when pressure, and therefore body heat, is applied. The polyurethane foam reacts to the heat, increasing the material’s viscosity and elasticity to contour closely.

When the pressure is removed, memory foam returns slowly to its original shape. The feel and responsiveness of a memory foam layer will depend on how it’s manufactured and how dense it is. The higher the density of the memory foam, the firmer the foam will be and the less it will respond and conform when pressure is applied.

What’s the Difference Between Foam and Memory Foam?

When people talk about ‘regular foam’ that’s used in mattresses, they’re often referring to polyfoam. Technically, memory foam is considered a type of polyfoam, but the two materials differ in feel, breathability, and more.

Polyfoam is an umbrella term that refers to any material that contains polyol and diisocyanate. It therefore includes polyfoams, latex foams, and memory foams. Both high- and low-density polyfoams are found in mattresses, with more supportive, denser polyfoams almost always found at the support core of all-foam styles.

Memory foam is a high-density polyfoam whose added chemicals give it a slow response to pressure, giving it the advantage of contouring more closely than polyfoam. Polyfoam, on the other hand, offers better responsiveness, temperature neutrality, and ease of movement.

Pros and Cons of Memory Foam Mattresses

Pros:

  • Conforms closely to a sleeper’s body.
  • Isolates and absorbs motion as sleepers shift positions in bed. Low motion transfer is especially appealing for couples.
  • Virtually silent when bearing weight.
  • Can help alleviate chronic back pain and aches.
  • Side sleepers and lightweight sleepers appreciate memory foam as a soft, conforming comfort layer.
  • Easy to compress for shipping, meaning customers can order them online as bed-in-a-box mattresses. 

Cons:

  • Memory foam retains more body heat than other foam types.
  • Can be expensive, with some models costing upwards of $4,000.
  • Not as responsive as latex, innerspring, or hybrid mattresses, which can lessen their appeal for couples who prioritize sex.
  • Memory foam breaks down rather quickly and is not as durable as other foam types.
  • Off-gassing, or odor, potential is high for memory foam beds, and some mattresses may need up to a week to air out after arriving.
  • Prone to indentations over a shorter period of time.

Is Memory Foam Toxic?

The safety of memory foam mattresses varies widely depending on the brand and where it’s purchased. Memory foam is made through a number of chemical processes, but this doesn’t mean memory foam mattresses are inevitably dangerous. In fact, all foams – chemical or synthetic –contain chemicals.

The concern around memory foam’s safety comes from the strong off-gassing odor it tends to release and the fact that VOCs, or ‘volatile organic compounds’ are sometimes used in its creation. VOCs can break down over time and release gases. VOCs in memory foam can include CFCs, formaldehyde, benzene, methylene chloride, and more.

Consumers worry that the breakdown of VOCs in their memory foam mattress could cause health issues with prolonged exposure. To ensure your safety if you choose to purchase a memory foam mattress, we recommend looking for labels that ensure you’re purchasing a clean and pure memory foam mattress. These include CertiPUR-US, Greenguard, USA Certified Organic and Organic Content Standard 100.

For more information, read our article, “Is Memory Foam Safe?

Does Memory Foam Retain Heat or Sleep Hot?

Because memory foam tends to envelope sleepers’ bodies, it can retain heat and increase body temperature. This can be an issue for people who already sleep hot or tend to sweat at night. Thankfully, not all memory foam beds sleep hot.

Today, there are more memory foam mattresses on the market than ever that contain cooling materials and designs. Gel- and copper-infused memory foam mattresses, for example, contain materials that help draw heat away from the body. Other mattress manufacturers choose to make memory foam less dense or perforate it to encourage airflow and prevent the trapping of heat.

To ensure your mattress sleeps cool if you choose to buy a memory foam style, look for gel- or copper-infused all-foam mattresses or a hybrid mattress with memory foam layers. Hybrid mattresses have coil cores, which have significantly better airflow than polyfoam cores. Another option is to add a mattress topper that’s designed to dissipate heat and wick moisture.

Memory Foam Mattresses and Pain

Memory foam is lauded for its ability to provide relief for sleepers with chronic pain. Here’s an overview of how memory foam can help address different types of pain throughout the body.

Back Pain

Chronic back pain affects millions of adults and can disrupt one’s ability to achieve a good night’s sleep. The “right” memory foam mattress will depend on the intensity of pain, your sleeping position and your body weight, but most memory foam options contour to the low back without sagging excessively. This simultaneously encourages healthy spinal alignment and provides relief.

If you suffer from back pain take a look at our best mattresses for back aches.

Hip Pain 

Pain and discomfort around the hips can occur from various factors, ranging from a medical condition to an old injury. Memory foam mattresses can relieve hip pain by conforming to the body consistently in this area and evenly distributing the weight. If you’re a side sleeper with hip pain, it’s recommended that you sleep with the ‘bad’ hip facing up, regardless of the type of mattress you select.

Hip pain a problem for you? Our best mattresses for hip pain can help.

Related: Hip Pain and Sleep

Arthritis 

Arthritis can wreak havoc on the body in many forms, and many varieties are characterized by similar symptoms such as pain, stiffness, and swelling. Look for memory foam mattresses with two or more comfort layers. These will conform closely to the sleeper’s body for improved spinal alignment and targeted pressure relief.

Head over to our best mattress for arthritis page for more information.

How are Memory Foam Mattresses Made?

Memory foam mattress manufacturers either source their memory foam or create their own proprietary memory foam in-house, but all memory foam products are made through a process of layering memory foam and other materials.

In all-foam mattresses, high-density polyfoam is almost always used as the base layer and the support core. This is because polyfoam offers better support and durability than even the densest memory foam, ensuring that the mattress not only lasts a long time but is supportive enough for the sleeper’s body.

The introduction of memory foam typically begins at the transitional layer or the comfort layer level. In most memory foam beds, multiple layers of memory foam are used one after another to create the deep-sinking, cushioned surface that attracts so many sleepers.

Memory foam beds are encased in covers made from cotton and other textiles, some of which can be unzipped and removed for spot cleaning or machine washing. If you purchase your memory foam mattress online, it will most likely be compressed and rolled for shipping. It will be sent as a bed-in-a-box, arrive at your doorstep as such, and will need to be unrolled and given up to 72 hours to expand and return to its original shape before it can be slept on.

A Few Memory Foam Mattresses We Love

If a memory foam mattress appeals to you for its pressure-relieving hug, here are a handful of memory foam styles we recommend from some of the best mattress companies on the Internet.

  • TEMPUR-Pedic—Our luxury pick, TEMPUR-Pedic offers memory foam mattresses that excel in cradling the body, aligning the spine, and alleviating pressure points. They also provide excellent motion isolation, are silent and come in a wide range of models and firmness settings.
  • Layla—The Layla features a dual-sided design and copper-infused layers, meaning that you’ll have your choice of two firmness settings in one mattress and will sleep relatively cool on either side. The soft side is best for side sleepers, and the firm side is best for stomach and back sleepers.
  • Nectar—Memory foam mattress shoppers on a budget will love the Nectar’s gel memory foam for pressure relief. It contains five foam layers and is a middle-of-the-road firmness setting that can work for almost every sleeping position and body type.
  • Puffy Lux—Made with four proprietary foam layers, the Puffy Lux is designed for side and lightweight sleepers. It doesn’t sink as much as traditional memory foam, giving it a more supportive feel than most memory foam options.
  • Loom & Leaf—Most consumers tend to equate memory foam with a very soft mattress, but that isn’t always the case. The Loom & Leaf provides a firmer option for strict back and side sleepers who love the viscous feel of memory foam. It’s also a good option for those who sleep with a partner, as it isolates motion very well.
  • Nolah Signature 12—This medium-soft, double-sided mattress features four layers of foam and an organic cotton cover. The comfort layer contains Nolah’s proprietary AirFoam, which is cooling and motion isolating. While technically not memory foam, the AirFoam has a similar feel without the heat-trapping chemicals that memory foam contains.

For more of our memory foam mattress picks, visit our list of the best memory foam mattresses of 2021.

The Bottom Line

If we’ve piqued your curiosity about memory foam, be sure to check out our top memory foam mattresses and our picks for the best memory foam pillows, If you’re still not sure memory foam is the best mattress type for you, our Types of Mattresses buying guide will shed light on the types of mattresses available and the pros and cons of each style. Even if memory foam isn’t the right mattress fit for you, we can help you find a mattress style that works for your specific sleep type and body type.