How Memory Foam Works

Are you looking to improve your sleep and interested in the pros and cons of a memory foam mattress? Here’s how memory foam works and why you might (or might not) want to give it a try.

By Sheryl Grassie

Apr 11th, 2022

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Memory foam is the colloquial term for a synthetic polymer known as polyurethane that has certain properties that make it a viscoelastic. To explain it a little less scientifically, memory foam starts as a liquid mixture of hydrocarbons from petroleum and water that becomes a thick heavy spongy material when poured into a mold and dried.

Just like a sponge, it dents with pressure and springs back to its original form when the pressure is released. It has a unique quality that makes it feel almost tacky or sticky, and it holds you in place. The heat and weight of your body allow you to sink into the foam. When weight and heat are withdrawn from the foam it returns to its original shape. The sticky sponge-like feel is the viscosity, and the springing back is the elastic quality, combined they give memory foam the scientific term viscoelastic.

Where Did Memory Foam Come From?

Memory foam resulted from research in the space industry during the 1960’s. NASA needed a way to cushion impact for astronauts. They developed a type of memory foam and eventually released the recipe to the public in the 1980’s. It was further developed by Fagerdala World Foams, a Swedish company that refined the formula and, after work of more than a decade, launched the first memory foam mattress for purchase.

The foam was originally referred to as “slow spring back foam.” In addition to mattresses, memory foam was used in all kinds of applications that require some degree of cushioning, such as sports helmets, shoes, and padded surfaces like an x-ray table or wheelchair seat.

The Pros and Cons of Memory Foam

Memory foam mattresses have a very different quality than other types of mattresses. They mold to your body supporting every surface in a way a regular spring mattress cannot. They eliminate pressure, and reduce pain, allowing for a deep level of relaxation that can dramatically improve sleep. Less pain, less discomfort, and less nighttime tossing and turning all support a better night’s sleep. The memory foam molds around your body, creating an individual custom cushion. This is a unique characteristic of memory foam mattresses and highly advantageous for many people.

There are, however, things that make memory foam not the perfect fit for everyone. Memory foam can be hot, and for those already challenged with night sweats, hot flashes, or trouble regulating their temperature during sleep, they may want to think twice before buying. Also, what makes memory foam great for some is the reason others don’t like it, the feeling of sinking like quicksand into the mattress.

Overall, it is an individual preference. Here are the primary points, both pro and con, regarding how memory foam works and what makes it a good or bad fit for you.



All memory foam mattresses have a density rating. These ratings can help further customize the feel of your mattress and address things like weight or sleep position. What the density rating tells you is the concentration of foam per square foot. This is not the same as the firmness. Density is rated on a continuum from a very low 1.5 lbs. per foot to a high 5.3 lbs. per foot and which is better is a matter of individual taste. There is a cost difference associated with different densities.

Densities for Memory Foam
Low-Density Under 3.0 lbs. per ft.
Medium-Density 3.0 – 4.5 lbs. per ft.
High-Density 4.5 – 5.3 lbs. per ft.

Reduces Pain

Memory foam is an amazing pain reliever. It supports all your pressure points while you sleep and can dramatically reduce pain in shoulders, hips, neck, back, and legs. Do you have back pain? This material can work wonders. Go for high density for extra support.


Memory Foam is famous for how much overall support it offers the user. From head to toe, the viscosity hugs you and leaves no part of the body unsupported. It straightens the spine and allows for better blood flow. You may have heard that this mattress is great for backs, and another type is great for something else, well memory foam is great for your entire body.

Hypoallergenic and Natural Bug Repellent

It is true that memory foam is wonderfully free from most allergens like dust mites, and it repels bed bugs. Bugs can still set up home in the frame surrounding your mattress, so be aware of that. Overall, these mattresses are a good choice for reducing allergy problems.

Motion Isolation

A wonderful feature of memory foam, especially if you sleep with another person or any type of four-legged creature, is the lack of motion transfer. You can impact one side of the bed by, for example, sitting on the edge, and no motion will transfer to the other side. This means you aren’t disturbed by your partner rolling over, your dog hopping on and off, or even kids jumping on the bed.

Durable and Low Maintenance

Memory foam mattresses are considered very durable and low maintenance because they don’t break down and often don’t need either rotation or flipping. This is good because memory foam mattresses are heavy and somewhat difficult to move. In general, there is nothing to do but enjoy them.

Sleep Position

The position you sleep in, back, side, or stomach can be a determinant in the type of mattress you choose. With memory foam all sleep positions are well accommodated.



The number one downside cited by customers, is temperature. If you run hot at night, memory foam may not be a comfortable fit. Although, in later iterations of these mattresses, there is a gel version that can mitigate some of the hot effects of memory foam. If you don’t like sleeping hot, consider an alternative because that is just how most memory foam works.


The off-gassing or fumes emitted by memory foam can be strong and are considered toxic. Due to the nature of the materials’ flammability, flame retardants are added to some memory foams. These and other chemicals associated with the manufacturing of polyurethane can be a health hazard. If you have chemical sensitivities or health concerns, then look to buy an organic mattress instead.

Hard to Clean

Memory foam does not like water or liquids, so it is best to keep it covered with a waterproof pad. Because of the porous nature of the material it absorbs stains and can be difficult to clean.


Memory foam has traditionally had a higher price tag attached than some other kinds of mattresses. The price will vary some based on the density with lower densities being less expensive and higher densities being more expensive. They are longer lived than most types of mattress, which can factor into the cost.


That feeling of sinking into the foam, some people do not like it. It can be claustrophobic, especially if you have trouble moving. Seniors as a group are slightly more disinclined to enjoy memory foam as well as combination sleepers who might find it difficult to rotate from side to side during the night.


The mattress industry is always searching for ways to help you get a better night’s sleep. Memory foam mattresses, which came on the market in 1992, have been trending ever since. They accomplish just that; a better night’s sleep. They work in a unique way in relation to body heat and weight, loosening and creating a form fit that offers incomparable support for all parts of your body.

They help reduce pain, are hypoallergenic, motion stable, and durable. They can run too hot for some, have fumes, are hard to clean, and are somewhat more expensive. Some people don’t like the sinking feeling that is a hallmark of memory foam. Overall, however, they work in a miraculous way to support your body and improve your sleep.