Everything You Need to Know About Memory Foam Mattresses
Astronauts not only landed on the moon—they're also (indirectly) responsible for changing the way Americans sleep. In the 1960s, NASA commissioned researchers to develop seating foam that would keep test pilots better cushioned during flights. They came up with memory foam (originally called “slow springback foam"), and the rest is history. The material is now used in everything from mattresses to movie theater seats to football helmets.
The innerspring mattress might still be the most popular sleep surface (it, too, was inspired by transportation—in this case, buggy seats of the 1800s), but memory foam is the fastest growing category of bedding. In fact, Research and Markets projects that the memory foam mattress and pillow market in the United States will reach more than $8 billion by 2023.
If you're considering a new memory foam mattress, here's everything you need to know, from what's between the covers to how to assess quality to which type of sleepers memory foam suits best.
What is a memory foam mattress?
A memory foam mattress is one made from viscoelastic foam, a type of high-density polyurethane foam. (Greener versions of memory foam use plant-based ingredients like soybean oil in place of some of the petroleum derivatives.) Memory foam's distinguishing feature is that it softens in response to heat and pressure. That's what gives it the body-hugging feel many sleepers love.
Most memory foam mattresses aren't made solely from memory foam, though. If they were, they'd be so soft that you'd sink too deeply into the bed. Instead, premium memory foam mattresses feature layers of foams in varying thicknesses and densities for the optimal balance of comfort and support.
What's inside a memory foam mattress?
There are a handful of components common to most memory foam mattresses. The parts of a memory foam mattress are:
- support core (bottom layer)
- transition foam (middle layer)
- comfort layer (top layer)
The bottom layer is the support core, which is often made from polyurethane foam and is strong enough to support the body's weight, says Bill Fish, a certified sleep science coach and founder of the sleep website tuck.com. From there, you'll likely find a layer of transition foam, followed by a top comfort layer (or multiple layers) of memory foam.
When comparing memory foam mattresses, these are the key things to look for:
“While it isn't an exact science, the rule of thumb is that the higher the foam density the higher the quality and the heavier the mattress," says Fish. (Memory foam mattresses often weigh upwards of 100 pounds.) Higher density foam translates into a more durable mattress that should last you anywhere from 10 to 15 years. Fish suggests looking for foam density of at least 3 pounds per cubic foot. Premium memory foam has a density of 4 to 5 pounds per cubic foot.
Keep in mind that you may have to go digging for this info, though, notes Fish, as it's often not front and center. “By looking through the brand's website or speaking to their customer service team, you should be able to find this information the vast majority of the time," he says.
If you're shopping for a memory foam mattress, no doubt you've come across the trend of “beds in a box." “Many of today's popular memory foam mattresses are first compressed down to one inch, vacuum sealed, rolled, and placed into box prior to shipping," Fish says. They're then sent via UPS or FedEx to the customer's doorstep. While beds in a box are cost-effective and convenient, they are made with lower-density foam so that they can be squeezed into a box.
Memory foam firmness is measured in “indentation load deflection," or ILD. In layman's terms, that's how much pressure it takes to make a 25% indent in a 4-inch piece of foam. Quality memory foam has an ILD between 10 and 50. (The higher the ILD, the firmer the mattress.) Again, check the brand's website or reach out to customer support for the ILD if the info isn't readily available.
ILD can be useful as a point of comparison, but keep in mind that comfort is subjective. Whether you prefer a memory foam mattress with a lower or higher ILD will depend on whether you like a softer or firmer sleep surface. (Read our guide to finding the right comfort level for you.)
Types of memory foam
Within the memory foam mattress category, there are a few varieties.
Traditional memory foam
Also known as viscoelastic foam, traditional memory foam is made from polyurethane, a petroleum derivative. Because of that, it can sometimes give off a chemical smell—a process referred to as off-gassing. That's the term for what happens when volatile organic compounds (VOCs) leak out of mattress foams into the air you breathe. Common VOCs include formaldehyde, toluene, chlorofluorocarbons (CFCs), benzene, trichloroethane, and perfluorocarbons. Although there's no evidence that off-gassing can have permanent effects on your health, it does contribute to indoor air pollution and is potentially irritating to people with chemical sensitivities or breathing issues. (Learn more about off-gassing here.)
Gel-infused memory foam
Newer types of memory foam often contain materials that help keep you cool while you sleep, since one of the biggest complaints about memory foam is that it sleeps hot. These materials are designed to absorb and conduct heat away from the body. “The top layer of foam normally contains some form of cooling properties, whether injected with gel, graphite, or even copper," Fish says. Cooling gel can either be mixed into the foam (infused) or applied as a layer on the surface (laminated).
Eco-friendly memory foam
"Greener" memory foam uses plant-based ingredients, such as soybean and corn oil, in place of some of the petroleum derivatives. To find a healthier memory foam mattress, look for one that has certified low-VOC foams. One such certification is Certi-PUR. Foams that carry this label are free of CFCs, formaldehyde, phthalates, and polybrominated diphenyl ethers (PBDEs, a class of chemical flame retardants banned in the United States since 2005). As an added bonus, eco-friendly foams feature a more open-celled structure, so they are more breathable, allowing you to sleep cooler.
There are some extra features you can look for in a memory foam mattress depending on your needs and preferences.
The lumbar region of your back is located just above your hips. Lumbar support is crucial in order to preserve the natural curvature of the spine. Without it, your midsection (where most people carry their weight) will sink into the mattress and pull the spine out of alignment—a long-term recipe for back pain. Memory foam conforms to support your spine, maintaining natural alignment and alleviating back pain. Some memory foam mattresses have added lumbar support in the center third of the bed.
All of the layers and components in a mattress come wrapped in an outer cover. For maximum sleep comfort, the cover should be made of a material that is soft, breathable, and moisture-wicking. (Learn why organic cotton makes an excellent cover material.)
Learn More About Saatva's Memory Foam Mattress
The benefits of a memory foam mattress
There are several reasons why you might want to choose a memory foam mattress over another type of bed. Here are some of the biggest benefits of sleeping on a memory foam mattress:
Memory foam mattresses relieve joint pain
“People with joint pain will appreciate the conforming ability of a memory foam mattress, as it gives the feeling of hugging the pressure points of the body," says Fish. (Here are more tips for sleeping better with chronic pain.)
Memory foam mattresses provide spinal support
Memory foam conforms to your body, helping to keep your spine in neutral alignment. This ensures you won't wake up with a sore back.
Memory foam mattresses limit motion transfer
With a memory foam mattress, you won't have to worry about being woken up by a partner in the middle of the night if they get out of bed. “Because the mattress isn't tied together in one consecutive coil system, if your partner gets up to use the restroom in the middle of the night, you aren't going to feel a thing," Fish says.
Memory foam mattresses are good for allergy sufferers
Unlike innerspring mattresses, memory foam mattresses don't have a lot of have nooks and crannies that dust mites can live in, meaning it can be a better option if you suffer from allergies.
Memory foam mattresses are durable
A well-made memory foam mattress should last 10 to 15 years.
The drawbacks of a memory foam mattress
There are pros and cons to every type of mattress. A memory foam mattress may not be right for you if:
You sleep hot
By design, memory foam responds to temperature, softening as it warms and molding to your curves. While that contouring ability is one of its most beloved features, memory foam can trap and retain heat close to your body, so you might want to consider another option if you sleep hot.
You weigh more than 200 pounds
“A memory foam mattress is better suited for sleepers under 200 pounds," says Fish. “Anything higher and there is the potential for the sleeper to 'bottom out' on the mattress and not receive the necessary support."
You like a bouncy feeling
Innerspring mattresses are known for their responsiveness, but that's not the case for memory foam. If you like the springy feel of a traditional mattress, you may not like the feel of memory foam. Keep in mind that that bouncy feeling is something many couples look for when it comes to sex.
Memory foam mattress ideal sleeping positions
One of the reasons memory foam continues to grow in popularity is that this type of bed supports a wide range of sleep styles.
Within the memory foam category, look for these features depending on your preferred sleep position:
If you're a side sleeper
Side sleepers benefit from snoozing on a softer memory foam mattress that keeps their spine in alignment while cushioning shoulders and hips. Look for added support in the lumbar region to protect the heaviest part of your body.
If you're a back sleeper
Anything too soft will cause you to sink into the bed, while anything too firm will put too much pressure on your shoulders and back, causing soreness when you wake up. If you're a back sleeper of average weight, look for a medium-firm memory foam mattress.
If you're a stomach sleeper
Because memory foam molds to the shape of your body, you may not like the feel of it if you sleep on your stomach. If you're still interested in memory foam, look for one that's firm enough to give you the support you need. Anything from a medium-firm to firmer mattress is what you'll want.
The right box spring for a memory foam mattress
Speaking of support, your mattress needs it too. A memory foam mattress is usually paired with a mattress foundation (a.k.a. box spring) or base. It can also be paired with an adjustable base. (Mattresses that are compatible with an adjustable base will bend and flex on the base without slipping or damaging the materials or structure of the mattress.) An adjustable base can help you get into an ideal sleep position. By allowing you to elevate your head, an adjustable base can also help with snoring and acid reflux.
Learn More About Saatva's Adjustable Base
The fine print
If you've made it this far, we know you're serious about your memory foam mattress purchase. In addition to materials and construction, there's one more important set of criteria to review: policies around delivery, home trials, returns, and warranties. Before you hand over your credit card number, check out our Guide to Mattress Fine Print.
Here's how our memory foam mattress compares to others on the market: