Updated at: 07-04-2023 - By: Helen Skeates

The viscoelastic substance used to make memory foam mattresses responds to body temperature. When you lie down on a memory foam mattress, it conforms to the shape of your body, and when you get up, it springs back to its original shape thanks to its viscoelasticity. Comfort and portability are two of the most prominent features of a memory foam mattress’ reputation. To facilitate transport, the memory foam can be compressed by the manufacturer by being deflated, folded, and placed in a box. This is why some people refer to memory foam as “bed in a box.”

Manufacturers claim that it takes a memory foam mattress anywhere from 24 to 72 hours to fully expand, but that it can reach 90% expansion in as little as 6 hours. When exposed to room temperature, memory foam mattress toppers need 24 hours to fully expand. Due to their higher density, memory foam pillows need between 48 and 72 hours to reach their maximum size.

We’ll talk about some of the additional considerations that can affect how long it takes for memory foam products to expand.

What is Memory Foam Made Of?

First things first: how does memory foam work in practice?

Memory foam is made primarily of polyurethane, a type of polymer (a substance having huge molecules comprised of many small, similar subunits bound together). Sofas, beds, insulation, liquid paints and primers, spray foam, elastic fibers, automobile parts, and even tough elastomers like roller blade wheels can all be manufactured using polyurethane, a very common and versatile plastic polymer.

Viscoelastic polyurethane foam, often known as memory foam, is a type of low-resistance polyurethane foam (LRPu). Depending on the type of foam being made, different chemicals and additives are combined with polyurethane to produce the finished product.

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Viscosity and elasticity, two of memory foam’s most important characteristics, are altered by these compounds. By “viscous,” we mean that it takes memory foam a long time to change shape under pressure or to transfer energy from one location to another. A material is said to be elastic if it can be stretched or bent without permanently altering its shape or size.

There is no standard “recipe” for making foam because each producer uses somewhat different ingredients and manufacturing techniques. Each memory foam product has its own unique feel and function thanks to its own unique recipe and manufacturing technique, both of which are well guarded trade secrets. However, most memory foam mattresses employ a viscoelastic foam that includes at least some polyether polyol. This chemical contributes to the foam’s elasticity and viscosity.

How Does Memory Foam Work?

As we’ve discussed thus far, memory foam mattresses are constructed to gradually contour to the shape of the sleeping individual in order to distribute weight more uniformly. They’re also built to bounce back to their original form when released from the stress of being worn.

Memory foam’s response varies with the amount of force applied to it. The foam is more “reluctant” to change shape under rapid pressure. Because of this, memory foam was first implemented in fields like space shuttle construction because of its exceptional ability to absorb impact force. This property of memory foam makes for a more uniformly cushioned sleep surface and gives rise to the gradual contouring sensation as the mattress responds to your weight and shape.

The average time it takes for memory foam to recover to its normal shape after being deformed is 5-10 seconds. Impact energy is absorbed and released during this time of recovery. This temporal lag, a process known as hysteresis, helps cushion sleepers because it removes some of the pressure (or, impact energy) created by the prone body.

Also crucial to memory foam’s functionality is the fact that its viscosity reduces as its temperature rises. Thus, when its temperature rises, its rigidity decreases and its flexibility increases. Because your body heat warms the sleep surface, a memory foam mattress will feel softer or more malleable after being used for a while.

Different Types of Memory Foam Mattresses

There is a vast range of memory foam mattresses on the market today, each with its own unique dimensions, forms, and production methods. There are a few distinct families of memory foam that go beyond the proprietary variations in chemicals and manufacturing methods that distinguish one product from another.

Types of Memory Foam

In general, three varieties of memory foam can be distinguished:


This is the very first generation of memory foam. It was the first memory foam available to the general public. The above describes the standard design and construction of memory foam that is intended to conform to the shape of the user’s body. Traditional memory foam has a problem with heat retention, which can make mattresses with such foam uncomfortable to sleep on. These concerns inspired the development of two additional memory foam options.


Open-cell memory foam is made from the same materials as conventional memory foam, but it has a distinct internal structure. The internal pockets (or “open cells”) of an open-cell memory foam mattress allow for ventilation and air flow, which aids in heat dissipation.

Early versions of open-cell memory foam mattresses were significantly less dense, which could influence the mattress’ firmness and support. However, cutting-edge manufacturing techniques have been refined to resolve this problem while keeping the mattress’s airy, open design (and therefore retaining the cooling effect).


Gel is also used in the manufacture of another kind of memory foam. Microbeads made of gel are often pumped into the mattress foam to give a gel layer. The microbeads make little sacs that are reminiscent to those seen in open-cell mattresses. These gels are typically “phase-changing” polymers, meaning they actively absorb and release heat from your body, as opposed to merely letting air through the mattress.

Many contemporary memory foam mattresses contain several, if not all three, of these types of foams, while others use foams that fit into only one of these categories.

These three varieties aren’t all there is to memory foam mattresses; some manufacturers now incorporate different materials, usually with cooling in mind. Copper is one of these materials. Because of its high conductivity, copper enhances the cooling and moisture-wicking properties of memory foam mattresses. Copper is used in the manufacture of mattresses that are a match for all three of the most common varieties of memory foam.

More environmentally friendly foams are being developed, and this is another emerging trend in memory foam. These greener memory foam mattresses use more plant-based components than traditional memory foams. It’s possible, for instance, that they’ll switch out some of the chemicals and derivatives used in conventional memory foam production for ones derived from, say, soy or maize oil. These methods of production are still in their infancy, but they are rapidly spreading as new technologies emerge.

Mattress Construction

There are various applications for memory foam in mattresses. As an example, there are a variety of memory foam mattresses on the market, each with its own unique construction and set of desirable features. Although each memory foam mattress has its own unique features, they all generally adhere to the same general design. There are three parts to the pattern:

  1. The comfort layer, or top layer, of a mattress consists of one or more foam layers designed to mould to the body and cushion it, depending on the mattress’s hardness level. Cooling foams are used in this area of many mattresses.
  2. As the name implies, the transition layer acts as a buffer between the softer comfort layers and the firmer support core. They are often slightly stiffer than the foam comfort layer and aid in dissipating body heat.
  3. The “core” of a mattress. Consisting of denser foam, this is typically the thickest section of the mattress. It works with the other foam layers to keep the mattress sturdy and comfortable. Some mattresses, known as hybrids, have a core similar to that of an innerspring mattress rather than foam. This usually results in increased stability, rebound, and airflow.

Qualities of Memory Foam

Now that we have established what memory foam is, we can move on to discussing the experience of sleeping on a memory foam mattress. There are three key features that characterize memory foam mattresses as a whole, though different models will provide varying degrees of these features.

  • The name “memory foam” itself alludes to one of its defining features: its ability to conform to the shape of the user’s body. When lying on a memory foam mattress, the surface will conform to the unique shapes of your body.
  • In addition to conforming to the shape of the sleeper’s body, memory foam often has what is known as a “sink” to it. This is the sensation of being enveloped by the mattress and even sinking partially into it.
  • As was noted above, memory foam is highly responsive to pressure; when you lie down on it, you’ll feel it soften and become less viscous in reaction to your weight and body heat.

Memory Foam Pros and Cons

Memory foam mattresses, in addition to its distinctive feel, are distinguished by a number of other features that might either endear or alienate potential buyers. There are those who absolutely enjoy memory foam, and those who absolutely despise it. Some users really enjoy the memory foam’s bouncy feel, while others find the material’s stiffness to be a drawback. As a result, it’s vital to discuss both the advantages and drawbacks of memory foam.

Memory Foam Pros

Memory foam molds to the shape of the body, relieving pressure in that area by utilizing the body’s own heat and pressure to mold to the user’s exact specifications. The hips, shoulders, and neck, among other pressure points, may feel some alleviation as a result. Regular, excessive pressure on those areas might lead to discomfort upon waking, difficulty falling asleep, and trouble staying asleep.

Memory foam’s contouring properties can relieve pain and discomfort for some persons, especially those with joint pain or arthritis, by redistributing body weight away from sensitive pressure points.

One further benefit of memory foam is that it helps to keep your spine in alignment and provides lumbar support for many different types of sleepers because of its conforming nature. If you sleep on memory foam, which conforms to your body’s shape, you may find it simpler to find a position that prevents your spine from curving too much as you sleep. This has the added benefit of reducing back discomfort and morning stiffness, both of which can lead to a more restful night’s sleep.

A lot of memory foam mattresses are hypoallergenic, which is great news for allergy sufferers. Memory foam mattresses are less prone to attract and accumulate allergens like dust mites, mildew, and other common irritants because of their dense structure.

One of the most crucial factors to consider when buying a mattress for a pair is how well it isolates motion, especially if you have trouble sleeping through your partner’s movements.

Memory foam is superior to traditional mattress materials in terms of reducing motion transmission. Memory foam’s density and the way it responds to and distributes pressure do a superb job of preventing motion transfer from one side of the bed to the other.

Memory foam mattresses have the additional benefit of being exceptionally silent. Anyone who wants to avoid the squeaking, groaning, or other noises that can come from a noisy bed will find this information useful, but it’s especially useful for couples who don’t want to wake each other while getting out of bed.

Memory Foam Cons

Memory foam mattresses have a reputation for being too hot to sleep on due to the amount of body heat they retain. Traditional memory foam, in particular, can become rather warm due to the material’s density and the fact that it is engineered to react to the body’s heat.

Despite advancements in memory foam technology (including open cell and gel foams, and other cooling construction methods) designed to solve this issue, memory foam mattresses still often retain heat more than other types of mattresses. If you’re already prone to overheating while sleeping, this could make falling asleep and staying asleep a challenge.

Memory foam mattresses are more expensive than other types of mattresses, which is another drawback. This is especially true if you choose a high-end memory foam mattress, which typically costs more than, say, an innerspring mattress of the same quality.

As memory foam mattresses become more widespread, and especially as mattress-in-a-box companies are becoming more popular, the general cost of memory foam mattresses has gone down. However, it is still generally the more expensive choice.

The general cost of memory foam mattresses has gone down as their availability has increased, particularly with the rise of mattress-in-a-box firms. However, it is still the pricier alternative.

Memory foam mattresses have an off-gassing and odor problem when they are first made. That’s called “off-gassing,” by the way. Usually the odor dissipates within 24 hours of unboxing, but occasionally it lingers for weeks. Less expensive memory foam mattresses off-gas more heavily and for longer.

Many memory foam mattresses today are sold as “mattress in a box” sets, giving the false impression that they are lightweight and easy to move. But this is rarely the case. Memory foam mattresses, after assembled, typically weigh more than other mattress materials.

This can be a problem when you need to move the mattress to replace the sheets or if you just want to rearrange the bedroom. Moving can be a significant hassle as well, especially if you have a mattress that came in a box, because removing it from the room will be much more difficult than bringing it in.

How long does it take a memory foam mattress (or mattress-in-a-box) to expand?

As was previously said, memory foam mattresses need up to 24 hours to fully expand. When memory foam is removed from its packaging, the air that was compressed out of it begins to return to its open cell structure. When air begins filling the foam’s open cell structure, the material’s viscoelasticity causes it to expand to its original shape. As was said before, the memory foam’s expansion time may change depending on the specific product.

Here are three things that can affect how quickly memory foam products expand:

  • Because of the correlation between temperature and the rate at which memory foam expands, keeping the room warm is preferable for use of memory foam. When heated, a substance loses some of its viscosity and gains some fluidity, making it simpler to shape.
  • Memory foam manufacturers create products with varying densities. It takes more time for foam with a higher density to expand. Whether it be a pillow or a topper, it makes no difference. High-density foam is the most stable and gives the most noticeable support. It’s possible that this article on how to make the most of your tempur-pedic cushion will interest you.
  • The expansion time is also affected by the foam’s thickness or depth. It may take more time for a thick pillow to properly plump up. Very thin memory foam toppers will expand in a shorter amount of time than their thicker counterparts, both in terms of time and actual thickness. Memory foam mattresses and toppers can be reduced to size if they are too thick for your liking.

What happens if you don’t wait for 24 hours for the memory foam to expand fully?

Most memory foams require a full 24 hours to reach their full size, as instructed. If there are any flaws in the mattress, they will be revealed once it has been fully extended. Sometimes, faults and fissures don’t become apparent until the product is fully stretched.

However, the memory foam will not be compromised if you choose to ignore this advise and utilize it before the 24-hour mark. It’s true that your body heat will cause the memory foam to expand more quickly. We recommend waiting at least 4-12 hours before using the mattress, but 24 hours is preferable.

Most of the expansion occurs in the first four to six hours after unpacking the memory, a time frame known as the off-gassing period. The term “off-gassing” refers to the release of chemical gases during mattress expansion. While not often harmful to healthy individuals, off-gassing can be unpleasant and even uncomfortable for those with asthma. The following article about off-gassing and mattress flammability may be of interest to you.

However, it’s worth noting that different brands of memory foam mattresses advertise vastly different expansion times, anywhere from 8 hours to mere minutes. Before making a purchase, we recommend getting in touch with the manufacturer to ask any and all questions you may have.

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How long does it take a gel memory foam mattress to expand?

To fully expand, gel memory foam needs at least 48 hours. This timeframe is approximate and may change depending on factors such as foam density, ambient temperature, and humidity.

Due to its higher density, gel memory foam may take somewhat longer to expand than standard memory foam. When compared to traditional memory foam, the primary distinction between gel memory foam and standard memory foam is the presence of microscopic gel particles in the former.

As a result of the inclusion of these particles, this memory foam stays far cooler than its conventional counterpart. The higher density of gel memory foam means it can handle more weight.

If your memory foam mattress topper isn’t expanding, try these solutions: (also applies to mattresses).

How to make memory foam mattress expand faster?

When you get a brand new bed, it’s hard to wait. It’s best to test out how comfortable it is by lying down on it right away. However, you should wait for the mattress to fully expand before using a memory foam mattress, mattress topper, or pillow.

Here are several ways to speed up the expansion of memory foam:

  • Quick! Take the Mattress Out of the Box
  • Spread it out and lay your bed flat.
  • A warm environment is essential.
  • Ventilate and circulate the air on the mattress.

Unbox the Mattress Right Away

If you do not want to wait too long before you can use your memory foam mattress, make sure to unbox it as soon as you receive it. The sooner you take it out of the box, the sooner you may begin the process of expanding it.

Make sure the room is warm

Make careful to unbox your memory foam mattress as soon as you get it if you don’t want to wait too long to start using it. The sooner you remove it from the packaging, the sooner the expansion process can begin.

Warmth also aids in maintaining the mattress’s softness once it has expanded.

Provide proper air circulation and ventilation for the mattress

Memory foam’s expansion time can be cut in half with the help of another technique: allowing air to circulate through it. A well-ventilated location (such a platform bed with slats) is one option, and fans can be used to further increase airflow.

To speed up the expansion process, fan heaters could be employed in place of standard fans. If you go this route, remember to use a low heat setting and double-check with the maker to ensure it’s safe for their product. According to the instructions for the sleep number, you should never place the device near a heater.

In-depth coverage:

  • How much money may be saved by using a mattress topper instead of purchasing a new mattress?

Does a warm room help make memory foam expand faster?

Having a memory foam mattress in a warmer environment will speed up the process of its expansion. Memory foam expands fine at ambient temperature but may expand more quickly if placed in a warmer environment.

Heat’s effect on memory foam is not limited to the initial phase of expansion; rather, it aids in maintaining the foam’s suppleness throughout time by lowering its viscosity and increasing its fluidity. You can keep your memory foam at a comfortable temperature by keeping it in a warm room. Because different materials and components have varying thermal tolerances, it is important to read the product’s manual to find out what range of temperatures it can withstand without damage.

How to Pick The Right Memory Foam Mattress

If you think a memory foam mattress could be the best option for you, there is still quite a bit to learn before making your purchase. What to look for in a memory foam mattress, in broad strokes


There are a wide variety of mattress firmness options available. There is a common system for describing the firmness of mattresses, with numbers ranging from 1 (extremely soft) to 10 (very firm) (very firm). Some people prefer really firm mattresses, while others prefer very soft ones, and yet others prefer ones that fall somewhere in the middle.

The vast majority of mattresses sold in stores or online will have a description that places them on a scale from very soft to very hard. However, an Indentation Load Deflection (ILD) rating can be used in place of or in addition to the aforementioned information. Mattresses with a higher ILD rating are expected to be firmer than those with a lower rating. Each layer of a mattress (comfort, transition, support, etc.) receives an ILD score, and the entire mattress receives an overall ILD score based on this system of measurement. A mattress with an overall ILD of 10 would be very soft, whereas one with an ILD of 50 would be very firm. Use those criteria to determine what constitutes “the middle” for you.


How much actual foam is stuffed into each layer of a memory foam mattress is represented by its density. Memory foam is sold in a wide range of densities, typically expressed in pounds per cubic foot (PCF). Higher density foam typically retains its form, elasticity, and structural integrity for extended periods of time. But higher density foams also trap more body heat during the night.

A density of 3.0–5.0 PFC is optimal for minimizing the trade-off between longevity and heat retention if you are an average-temperature sleeper (i.e., you don’t sleep very hot).


The thickness of a memory foam mattress is measured in inches along its length and width. This is not the same as density; three inches of foam, for example, could have a score of 10 or 50 on the ILD scale. The typical thickness of a memory foam mattress is between 6 and 14 inches. Generally speaking, a thicker mattress will provide greater support than a thinner one, however the latter may be softer in some cases.

You shouldn’t just think about the overall thickness of the mattress, but also the thickness of each layer. Comfort and transition foams should total at least four inches in thickness and be placed between the mattress top and the foundation for the best results with memory foam mattresses. This ensures that the support core will do its job without making sleeping on the mattress unpleasant.

Standardized Testing Certifications

Additives in low-quality memory foam mattresses can shorten the mattress’s lifespan, reduce comfort, and potentially pose health risks through off-gassing and skin irritation. The Certipur-US accreditation is something to seek for when shopping for a new mattress. Memory foam mattresses with this certificate of certification have been manufactured without the use of chemicals known to be both detrimental to the mattress and to human health.

Mercury, lead, heavy metals, and formaldehyde are not used in the production of a Certipur-US certified mattress. They also don’t include any phthalates or PBDEs, two plasticizers thought to be hazardous to reproductive health (Polybrominated diphenyl ethers, a flame retardant that is banned in the US for negative health effects, but which is sometimes used in mattress manufacturing abroad). There is less of the chemical odor associated with off-gassing from these certified mattresses because of the low concentration of volatile organic compounds (VOCs).

Checking if a mattress is certified is worthwhile because it removes a potential source of concern about the product’s quality, durability, and safety.

Memory Foam Mattress Do’s and Don’ts

If you put in the time and energy to maintain your memory foam mattress, it will reward you with years of the optimal combination of softness and support.

Here are some easy things you should and should not do to maintain the quality of your mattress:

1. Do Rotate It Regularly

Unlike many other multilayer foam mattresses, our memory foam mattresses are not intended to be rolled over. However, to avoid depressions from forming in regions of intense pressure, we advise that you flip it head to foot every three months or so.

2. Don’t Get it Wet

Avoid getting any liquids on the mattress’s surface if at all possible, as this can cause the foam to degrade more quickly. If you tend to be a spiller, a mattress protector is a must to prevent this from happening.

3. Do Use a Suitable Bed Base

The bed’s base should be solid, level, and free of any large gaps. Slats on the base should be between 10 and 15 centimeters broad, with gaps of no more than 5 centimeters. A mattress with uneven support, such as that caused by wider gaps, would wear out more quickly. See this guide to learn how to choose the proper bed frame for your mattress.

4. Don’t Keep it Near Strong Heat Sources

Because of its sensitivity to body heat, Memory Foam conforms exactly to each individual’s unique outline. Keep your memory foam mattress away from any sources of intense heat.

Memory foam mattresses should not be used with any other type of powerful heat source, including electric blankets and hot water bottles, which can harm the foam’s structure and significantly reduce its lifespan.

5. Do Protect it With a Washable Mattress Cover

Many of our mattresses include a cover that can be removed and washed to keep it smelling fresh and protected from spills and stains. Washing at 40 degrees will help maintain a clean mattress for a longer period of time.

6. Don’t Make Your Bed!

And finally, we know it goes against every rule in the book, but we suggest you delay making your bed in the morning. Because of this, any nighttime perspiration will be able to evaporate off your mattress and linens.

Memory Foam Mattress FAQs

Years in the memory foam industry have exposed us to a wide variety of inquiries. Let’s put a few on the record;

How Long Will a Memory Foam Mattress Last?

A decent memory foam mattress, if carefully cared for, has a lifespan of 15 years or more.

You may expect your memory foam purchase to last for a long time if you choose with a higher density. Spending a little bit of money now will save you a lot of money in the long run by preventing you from having to buy a new mattress every few years.

How Often Should a Memory Foam Mattress be Turned?

Never! Turning a heavy mattress can be a hassle, but with our memory foam mattress, you won’t have to worry about that. Memory foam mattresses should be rotated every three months or so, from head to foot.

How Do You Maintain A Memory Foam Mattress?

By adhering to our list of what to do and not to do with a memory foam mattress! Memory foam, fortunately, requires almost no upkeep and is therefore easy to preserve in pristine shape.

How do you Deep Clean a Memory Foam Mattress?

Stains and spills are inevitable. The next time you need to give your mattress a thorough cleaning, use these methods;

  • Mattresses collect dust and dead skin cells, so to get rid of them, remove the sheets and vacuum with the brush attachment.
  • First, clean the mattress, and then sprinkle baking soda over it; let it like that for 24 hours to absorb any lingering odors. After that time, you may vacuum the baking soda off and enjoy your brand new mattress.
  • Make an eco-friendly stain remover by filling a spray bottle with a mixture of white vinegar and water, or a tiny bit of dishwashing liquid and water. Apply the cleaning solution to the affected area and scrub gently in circular motions with a clean sponge to remove the stain. Baking soda can be used to remove tough stains from a mattress after spot cleaning has been performed.

Does a Memory Foam Mattress Need to Breathe?

Yes. Having a well-ventilated space will keep you cool at night, prevent the growth of mold, and ensure a comfortable sleeping environment. A bed frame that allows air to circulate under the mattress is preferable.

IKEA Mattresses: Why You Can Sleep On Them Right Away – lietaer.com

How Do You Fix A Dip in a Memory Foam Mattress?

Memory foam mattresses might sink or droop if they are composed of low-quality foam and if they aren’t rotated as often as recommended.

Once the mattress begins to sag, your only real options are to replace it or add a comfort layer such as memory foam. If you take good care of your mattress, you won’t have this problem.


There are several factors to think about before, during, and after purchasing a mattress. That requires a lot of time and effort.

We addressed the issue of “how long does a gel memory foam mattress take to expand?”

I trust that this has been helpful to you.

As usual, the wait and the cost were well worth it. Just be patient for the next day or two and relish the chilly mattress in the meantime.