What is Memory Foam?

By McKenzie Hyde Certified Sleep Coach

Last Updated On October 11th, 2023
What is Memory Foam?

Key Takeaways

  • Memory Foam Characteristics: Memory foam is denser and more contouring than traditional polyurethane foam. It responds to heat and weight, molding to the shape of your body, making it popular for its comfort and support.
  • Types of Memory Foam: There are different types of memory foam, including traditional, open-cell, plant-based, and gel-infused. Each type offers specific benefits, such as improved breathability, reduced chemical usage, and enhanced cooling properties.
  • Pros and Cons: Memory foam mattresses offer pressure relief, motion isolation, and durability. However, they can retain heat, may have off-gassing odor initially, and are prone to water damage. Selecting the right firmness level and checking for certifications like CertiPUR-US® can help you choose the best memory foam mattress for your needs.

If your bed molds perfectly to the shape of your body, you’re probably sleeping on a memory foam mattress. Since its debut in the 90s, memory foam has become all the rage in the mattress industry and is now more popular than the traditional innerspring bed. It seems everyone is looking for the best memory foam mattress to suit their needs and achieve the elusive 8 hours of uninterrupted, good night’s sleep.

Memory Foam vs. Poly-Foam

Memory foam is denser than the traditional polyurethane foam. Polyurethane foam is a petroleum-based product and is both springy and bouncy in nature. Memory foam, on the other hand, is more contouring, so it adapts to a sleeper’s individual movements for ultimate comfort and support.

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Memory foam is polyurethane foam with added chemicals in place to increase the foam’s density and viscosity. The resulting product is often referred to as viscoelastic foam, and it responds to both heat and weight while molding itself to the shape of your body.

NASA Technology Goes into Memory Foam

Memory foam was first created for NASA in the 1960s before making its way into the mattress industry. Since memory foam was developed to be temperature sensitive, it was also known as “temper foam” or “slow spring back foam,” making it ideal for space travel. Memory foam molds to the shape of your body, but once the pressure is removed from its surface, the foam slowly returns to its original shape. This feature of memory foam makes it an endearing choice for mattresses.

What is Memory Foam?

Memory foam mattresses are good for those with back pain and are looking for lumbar support. It provides the right amount of cushioning with firmness to aid pressure relief.

Memory foam mattresses are denser and heavier than regular mattresses. The chemical composition of memory foam is different than other foam used in mattresses. Memory foam mattresses are available in varying firmness options and can be a good fit for almost any sleeper. Apart from being used in mattresses, memory foam is commonly used as mattress toppers and mattress pads.

Different Types of Memory Foam

With time, memory foam mattresses have evolved to cater to the distinct needs of different kinds of sleepers. Choosing a type of foam for your needs can be overwhelming, but we’re breaking down the options here to make it easier.


The traditional memory foam mattress was the first type of memory foam mattress to hit the market in the mid-1990s. This product quickly became popular because it negated the disadvantages of spring mattresses. The traditional memory foam mattress molds to the shape of your body, thus reducing the amount of stress you feel on the joints as you lie down on your bed to relax and rejuvenate for the next day.

The viscoelastic nature of memory foam enables it to provide customized support to your body. It hugs the natural contours of your spine, thus providing you with optimal support. Your body weight is evenly distributed as you lie down on the bed, which aids in improving blood circulation in your body.

Memory foam mattresses are also superb at isolating motion. Each individual cell of these mattresses work as shock absorbers by themselves, diminishing the chances of transferring motion from the source of its origin. This ability to isolate motion was seen as a huge advancement in the mattress segment— it calls for a peaceful night’s sleep even if you have a partner, kids, or pets tossing and turning next to you.

Moreover, memory foam mattresses are known to be antimicrobial because they limit the growth of bacteria, fungus or dust mites. These microscopic organisms are the leading causes of allergies and irritations. However, these microorganisms cannot survive in memory foam mattresses because they’re so dense.


The structure of traditional memory foam can cause overheating because it restricts airflow. For hot sleepers, this feature can be disturbing. To counter its effects, the open cell technology in memory foam mattresses was developed. This technology helps in absorbing and releasing heat easier than a traditional memory foam mattress.

The open-cell structure of memory foam mattresses allows for more breathability because the open cells enable heat to flow, instead of trapping it. This dissipates the heat and makes it feel cooler. Since open cells allow for better airflow, the response time of these mattresses is quicker. Like the traditional memory foam mattresses, even the open cell memory foam mattresses adjust to the shape of your body when you sleep on it, but it comes back to its original shape faster than traditional memory foam. Increased responsiveness prevents the feeling of sinking in that is sometimes associated with traditional memory foam mattresses, and it also adds to the durability of the product.


The plant-based memory foam has all the advantages of open-cell memory foam mattresses while seeking to reduce chemical usage to a certain extent. This kind of memory foam is made by replacing a portion of the petroleum products with plant-derived oils.

We’re a leading brand in the plant-based mattress segment. While most memory foam mattresses are 100 percent petroleum-based, we at Amerisleep substitute a fraction of that petroleum with plant-based castor oil in our Bio-Pur® layer. This makes it more sustainable and eco-friendly than regular open-cell memory foam mattresses.

Our Bio-Pur® layer on all Amerisleep mattresses bounces back ten times faster than traditional memory foam mattresses. It is also five times more breathable than traditional memory foam mattresses. Our Certi-PUR-US® certified plant-based foams are also free of chemicals like CFCs, formaldehyde, phthalates, PBDEs and are low in volatile organic compound (VOC) emissions. Plant-based memory foams mattresses strive to strike a balance between comfort and chemicals. The addition of plant-based products in these mattresses helps in cutting down the use of certain chemicals.


This technology in the memory foam segment became popular in 2011. Gel memory foam mattresses have a layer of cooling gel microbeads on either the top layer, near the top layer, or spread throughout the memory foam mattress. This kind of memory foam mattress has all the advantages of the traditional memory foam mattress while addressing the issue of heat retention.

These gel microbeads are made of “phase-changing materials”, which are nothing but chemicals with heat-absorbing properties. They prevent heat retention as experienced in traditional memory foam mattresses. These mattresses are also firmer than the traditional memory foam mattresses because of the presence of the gel microbeads. Though these beds may feel a little firmer, the inclusion of gel microbeads also speeds up response time, so you’ll never feel “stuck” in one of these beds.

The gel microbeads work on the principle of an ice-pack. They help in faster cooling, but once they reach the threshold, it stops working. Like how ice-packs stop working once they reach room temperature, similarly after their threshold these gel-infused memory foam mattresses lose their cooling abilities. But just how much is the threshold is yet to be quantified.

Pros and Cons of Memory Foam Mattresses

Memory foam mattresses address a lot of sleep concerns, but they also come with their fair share of disadvantages. In this article, we will dissect the pros and cons of memory foam mattresses.


Temperature and pressure-sensitive

Memory foam beds counter the springy and bouncy feel of regular polyurethane foam. It provides better support, making it more comfortable to sleep on. Memory foam responds to your body temperature and pressure and contours to the shape of your body, increasing the comfort of your mattress.

Pressure point relief

This mattress molds to the shape of your body, and in doing so, releases stress on pressure points. This feature enables in relieving joint aches or body pain.

Motion isolation

Each cell of the memory foam mattress works as a shock absorber, diminishing the effect of motion transfer. This makes it a good choice for a mattress for motion isolation with more than one sleeper. If your co-sleeper tosses and turns on the bed, your sleep will still not be disturbed.


Memory foam mattresses are dense, which contributes to their durability. The presence of more cells to conform and support the sleeper’s weight makes the mattress dense. Higher density translates to increased durability in the memory foam mattresses. On an average low-density foam tends to last about 4- 6 years, while medium and high-density foams last upwards of 8- 10 years.


The dense cellular structure of memory foam is responsible for its antimicrobial nature. It is an inhospitable environment for microorganisms like dust mites, bacteria, and fungi to thrive. These are leading indoor allergens that can cause eye, nose, and throat irritation.


Sleeps Hot

Memory foam mattresses have a tendency to trap heat because their foam layers are quite dense. When you lay on these beds, the foam molds to your body, leaving little room for heat to escape. Heat retention can lead to night sweats and uncomfortable, disturbed sleep. However, many modern mattress brands address this concern by including cooling technologies and plant-based foams in their beds.

Potential Off-Gassing

Memory foam is made by adding chemicals to polyurethane foam to give the foam viscous and elastic properties. When these chemicals break down, it results in off-gassing, or a “new mattress” smell. During this process, volatile organic compounds (VOCs) are emitted into the air and can cause nausea, headaches, or allergic reactions.

Off-gassing is not exclusive to mattresses, though you may have experienced this phenomenon after walking into a freshly painted room or after buying a new car. The off-gassing scent goes away after a few days, but if you find your bed continues to have a chemical-like smell for weeks after unboxing, we suggest reaching out to the brand about your concerns.

Prone to Water Damage

Memory foam, like most mattress materials, is not waterproof. That’s why we recommend always using a mattress protector that shields your bed from stains, moisture, and any other damage that could void the warranty.

Health Benefits of Sleeping on a Memory Foam Mattress

The memory foam mattress conforms to the shape of your body and gives you a cradling effect. So whether you sleep on your side, back or stomach, this viscoelastic foam molds to your shape and makes you comfortable without causing any pressure points. If you are a back sleeper, it offers good lumbar support— which is one of the many reasons memory foam beds are some of the best mattresses for back pain.

The cradling effect in the memory foam mattress ensures your body weight is evenly distributed on the surface of the bed. So no part of the body is left feeling unsupported.

Even distribution of body weight on the surface of the bed helps in relieving pressure from the sensitive and sore areas of your body.

Plus, if you use your memory foam mattress with an adjustable base, you can enjoy the benefits even more, since adjustable beds can help with pressure relief, back pain, poor circulation, and snoring.

Hot Sleepers on a Memory Foam Mattress

While traditional memory foam mattresses are known to retain body heat and cause night sweats, the good news is that this is partly a common memory foam mattress myth. There are now cooler alternatives in the memory foam segment for hot sleepers. Plant-based memory foams are known to mitigate the heat-trapping effect of traditional memory foam mattresses.

Many foam mattresses also incorporate temperature-regulating technologies such as cooling microbeads, graphite, copper, and phase-change fabric.

Is Memory Foam Toxic?

While it is true that chemicals are used in memory foam mattresses, these chemicals only pose a health risk in their raw, untreated form. This means that these chemicals are only a risk during the manufacturing process. Treated, cured chemicals rarely pose serious health risks; however, those with asthma or allergies may be more sensitive to the off-gassing scent these beds sometimes have. Not to fear, though, as the chemical-like off-gassing scent usually dissipates in only a few days. If you have asthma or experience allergies and are worried about sleeping on a memory foam mattress, we suggest talking with your doctor before purchasing one of these beds.

Another thing to consider is the third-party certifications these beds often have. Certifications such as CertiPUR-US® and OEKO-TEK test mattresses to ensure they’re safe from harmful chemicals such as ozone depleters, formaldehyde, mercury, lead, phthalates, PBDEs, and low in volatile organic compounds (VOCs). Choosing a memory foam mattress with one of these certifications should mean peaceful, allergy-free sleep.

Choosing the Right Memory Foam Mattress

Now that you know all the pros and cons of memory foam and the different types, how do you know which one is best for you?


Most mattress brands use a mattress firmness scale to differentiate between models. While yes, many brands only carry two or three models, some carry a lot more, and it’s important to know which one will fit your sleeping position, body type, and overall preferences.

The firmness scale ranges from 1-10, or soft to firm, with the following firmnesses recommended for certain body types and sleeping positions:

  • Soft (1-3): side sleepers, petite sleepers (130 pounds or less)
  • Medium-soft (4-6): side sleepers, combination sleepers, petite sleepers
  • Medium (5-7): side sleepers, combination sleepers, back sleepers, average weight sleepers (around 130 pounds)
  • Medium-firm (8-9): back sleepers, stomach sleepers, sleepers with back pain, heavyweight sleepers (230 pounds or more)
  • Firm (10): back sleepers, stomach sleepers, heavyweight sleepers


Memory foam is considered safe to sleep on, but if you want to take it step further, look for certifications like CertiPUR-US®, which ensures your foam is without heavy metals, phthalates, and any chemicals that can cause off-gassing.

You can also look into whether or not your mattress is made with plant-based materials.

When to Replace Your Mattress

There are a few telltale signs your memory foam mattress needs replacing. Most memory foam beds, even the high-quality ones, last between 7-10 years. If your mattress is older than that, it’s time to consider a new one. Here are some other signs it’s time for a new bed:

  • Sagging in the middle or soft spots throughout
  • A musty smell from sweat or oil buildup (use a mattress protector to prevent this)
  • Poor responsiveness or lack of support
  • You wake up with pain or feel tired after a full night of sleep

To prolong the life of your bed, use a mattress protector and make sure to put your mattress on a compatible foundation. Memory foam beds work with platform, slatted, and adjustable bases. If you use a slatted base, make sure the slats are no more than 2.75 inches apart to prevent sagging. You can find specific mattress foundation suggestions in your mattress’s warranty.


There are various types of memory foam mattresses available to suit different people. We suggest reading the product specifications and understanding what goes into making your mattress to choose the best mattress for your needs.

About the author

McKenzie Hyde is a Certified Sleep Science Coach and a full-time writer specializing in sleep health and the mattress industry. With a Master of Arts degree in literature and writing from Utah State University, McKenzie combines her passion for writing with her in-depth knowledge of sleep science. Her articles cover a wide range of topics, including best sleep practices for students, the consequences of sleep deprivation, and choosing the right mattress for back pain relief. McKenzie's dedication to delivering accurate and informative content makes her a valuable contributor to the field of sleep health.

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