Say “memory foam,” and most people flashback to that ’90s-era commercial featuring a woman jumping on one side of a bed and a glass full of red wine not spilling on the other. In mattress-speak, the wineglass trick illustrates the absence of motion transfer” in memory foam mattresses-what one sleeper feels (or, in this case, doesn’t feel) when the person on the other side of the bed tosses and turns.
The ability to limit motion transfer is what sets memory foam apart from other types of mattresses, says Terry Cralle, RN, a certified clinical sleep educator and co-author of Sleeping Your Way to the Top. Another standout quality of a memory foam mattress is the way it conforms precisely to all of your body’s curves. That contouring ability makes it ideal for pressure relief and a comfortable choice for all types of sleeping positions.
That said, not all memory foam mattresses are alike. Firmness, eco-friendliness, durability, and cost vary widely between brands. Here’s a closer look at what’s inside a memory foam mattress, and a few tips on how to select a memory foam mattress that will help you achieve the perfect sleep.
What’s in a memory foam mattress
Memory foam-also known as viscoelastic foam-is high-density polyurethane foam that softens in response to heat and pressure, which is what allows it to mold to a sleeper’s body. Engineers working for NASA developed memory foam in the 1970s when they were looking to invent a material that would provide better seat cushioning and crash protection for airline pilots and passengers. In addition to mattresses, pillows, and mattress toppers, memory foam is also used for furniture cushions and in some car upholstery.
Mattresses in the memory foam category are typically not 100 percent memory foam; the material is so soft that it wouldn’t provide enough support all by itself. Only the upper, or “comfort,” layers are memory foam. The rest is a support core that’s made from denser polyurethane foam or, in the case of a hybrid mattress, a combination of foam and innersprings.
Some memory foam mattresses have additional support layers of varying densities and special features like cooling gels or moisture-wicking fabrics, designed to combat the material’s natural tendency to trap body heat.
How to choose the best memory foam mattress
Memory foam mattresses range in price from a few hundred dollars to several thousand. So how can you be sure you’re getting the best value for the money?
The first thing to check is the density of the foam, expressed as the weight of one cubic foot of the material. Premium memory foam has a density of 4 to 5 pounds per cubic foot. The higher the density, the more supportive the foam and the more durable the mattress.
The next thing to consider before you buy a memory foam mattress, is the firmness. Firmness of memory foam is measured in “indentation load deflection,” or ILD. That’s a fancy term for how much pressure is required to make a four-inch indent on the mattress. Quality memory foam has an ILD between 10 and 50; the lower the ILD, the softer the mattress.
The comfort level you choose is largely a matter of personal preference-what feels soft to one person may feel rock-hard to another, Cralle points out-but if you’re heavier, for example, you may want a higher ILD to ensure you’re getting adequate support. (Here are some more helpful guidelines for choosing the right mattress for your body type.)
Finally, look for extra features that may be important to you, such as lumbar support, cooling gel layers, and breathable or hypoallergenic fabrics. (Sheets play an important role in your sleep too. Here’s how to choose the best sheets to suit your needs.)
Other memory foam considerations
Beyond the basics of foam quality and mattress construction, these are a few other considerations that might help you determine which memory foam mattress is right for you.
Memory foam can offgas
Memory foams are known for giving off a funky chemical smell, a process known as “offgassing.” Offgassing happens when volatile organic compounds (VOCs) created during the manufacturing process break down and get released into the air. Formaldehyde, perfluorocarbons, and PBDEs from chemical flame retardants are just a few common culprits.
To reduce or eliminate offgassing, some manufacturers use greener foam that contains plant-derived ingredients, such as soybean oil, in place of some of the petroleum-based derivatives. Saatva’s Loom & Leaf mattress, for example, is made with foam that carries the CertiPUR label, which means it is certified to be low-VOC and made without any harmful chemicals. Saatva foams are also stabilized before manufacture, so any offgassing happens before the mattress leaves the factory, and not shrink-wrapped in plastic, which can trap odors and make smells worse.
Memory foam can help with back and joint pain
The contouring quality of memory foam helps keep the spine in alignment and reduce pressure on sensitive joints. That’s why it’s often recommended for people who suffer from back pain. According to the latest research, a medium firm (rather than too hard) mattress is the best for back pain relief.
Memory foam can cost a lot-or a little
Because the cost of production can be less than other types, a memory foam mattress can be had online for as little as a few hundred dollars. But those less expensive mattresses are often made in places without strict health and safety standards, or made from low-density foam that has been compressed and packed into a box. Prices for a quality memory foam product can stretch into the thousands, but rather than focus just on cost, Cralle advises, take the time to learn about the materials and features, read quality reviews from customers (but stay away from comfort, which is subjective), and think about what really matters to you. That’s the best way to assure that you’ll be satisfied with your mattress for years to come.