Updated at: 25-04-2022 - By: Jane Brody

A sound night’s rest, was it? As Benjamin Franklin observed, “There will be enough sleep in the tomb.” Perhaps you’re following in his footsteps. When it comes to getting a good night’s sleep, most people agree that the best place to start is with their bed. For the rest of your life, you’ll sleep for an average of eight hours a night, which equates to around 25–30 years. Isn’t it logical to get the most comfy bed you can afford with all that lying around doing nothing? Memory foam mattresses, which adapt to your body like a second skin, are becoming increasingly popular. This material has a distinct memory, but what is it and how does it retain it? If you’d want to know more, let’s investigate!

What is Memory Foam Made Of?

To begin, what exactly is memory foam?

Polyurethane, a polymer (a substance with big molecules, comprised of many small, similar subunits bound together), is the major component of memory foam. This flexible plastic polymer can be used to make a wide range of items, from furniture to insulation to spray foam to elastic fibers to vehicle parts and even durable elastomers such as rollerblade wheels. Polyurethane is a common and adaptable plastic polymer.

The memory foam mattress explained - advice - Time4sleep

Memory foam is a type of polyurethane foam known as “viscoelastic” or “low-resistance” (LRPu). Polyurethane may be made into a variety of foams by mixing in various components and additives.

Ultimately, these compounds have an impact on the viscosity and flexibility of memory foam. This means it takes a while for memory foam to change shape under pressure or transfer energy from one area to another, which is what we mean when we say it’s “viscous.” By “elastic,” we mean that a material can stretch or contort without losing its original shape or size when a force is applied to stretch it;

In terms of the chemicals they utilize and the techniques they employ to make foam, different manufacturers follow different “recipes.” Each memory foam product’s feel and performance is influenced by its unique recipe and manufacturing process, both of which are closely guarded trade secrets. Most viscoelastic foam used in memory foam mattresses, on the other hand, contains at least a small amount of polyether polyol, a chemical that gives foam its elasticity as well as its viscosity.

How Does Memory Foam Work?

Memory foam mattresses, as described above, are made to conform to the shape of your body over time in reaction to pressure. They are also engineered to be durable and to recover to their former shape when the pressure and weight of the body is removed from them.

How much “force” you put to memory foam affects its response. The foam tends to change shape more slowly, or “reluctantly,” if you apply pressure immediately. That’s why it was first utilized in sectors like space shuttle construction, where memory foam absorbs the stress of an impact. A mattress made of memory foam has the ability to conform to the shape of your body as it reacts to the pressure it is subjected to and re-shapes itself to fit your curves.

When pressure is removed, memory foam takes 5-10 seconds to recover to its original shape. Energy from the impact is absorbed and dissipated during this period of recovery. A phenomenon known as “hysteresis,” this time lag reduces some of the pressure (or, impact energy) generated by the prone body, which helps cushion sleepers.

Memory foam’s viscosity reduces as the temperature rises, which is a crucial aspect of its function. In other words, when the temperature rises, it becomes less rigid and more pliable. Your body’s heat boosts the temperature of the sleep surface on memory foam mattresses, which makes them seem softer or more malleable after you’ve been lying down on them for a while.

What’s different about memory foam?

Your bones get in the way of getting a good night’s rest. In the absence of bones, it would be much easier to sleep. Imagine how much easier it would be to sleep if you were nothing but a blob of muscle and fat! Unfortunately, your skeleton is encased in a hard structure that feels as uncomfortable as a bicycle frame.

There are hundreds of individually coiled metal springs attached to one another in a “open or continuous coil” to support a mattress made of soft material in a typical bed. Your body’s shape won’t be taken into account when determining how much the mattress will give way under your weight. A backache the next day can be caused by a lack of support for some areas in the spine when you sleep on your stomach. Your hips and shoulders will bear greater weight when you sleep on your side, which might make you feel achy and uncomfortable. Together, you and your companion will likely roll into a valley in this mattress if you sleep on it. There are at least twice as many springs in a more advanced mattress (often up to 10 times as many), and each one is individually flexible. Springs of various gauge wire can be used to provide more or less support for specific regions of the mattress. Because of the additional springs, mattresses with pocket springs provide much better support, but they also tend to be heavier and more expensive. The higher the “spring count,” the better the mattress.

Memory foam is based on a basic concept. A thick layer of foam that gives way as you press down on it is an alternative to traditional spring mattresses. Technically, it’s called viscoelastic: visco (from viscous) means it moves, somewhat reluctantly, when you apply a force; elastic means it returns to its original shape when you remove the force. Because the foam is temperature-sensitive, as you warm it up, it sinks more deeply. You’ll be surprised at how quickly it conforms to your individual features. As a result of the foam sinking deeper into your shoulders and hips while you sleep on your side, your entire body should be well-supported and your spine should remain straight at all times. The pressure on your shoulders and hips is reduced since your weight is distributed more evenly. That’s why many people find memory foam mattresses help to reduce the symptoms of problems such as backpain and arthritis. If you change position or turn over, the mattress gradually molds to your new shape.

Simple as it is, the concept of memory foam is revolutionary. Your mattress is made of thick foam that gives way when you press down on it. “Viscoelastic” refers to the fact that the material returns to its original shape when a force is removed, which is why it’s termed viscoelastic. Warmth from your body causes the foam to rise and fall more rapidly. It conforms to your individual shape in a flash. To provide a straight spine and complete body support as you sleep on your side, the foam in the hips and shoulders seeps in deeper. As a result, pressure is removed from the shoulders and hips, where your weight is concentrated. Because of this, many people find that memory foam mattresses provide relief from the symptoms of ailments like back pain and arthritis. Memory Foam Mattresses After a few minutes of shifting positions, the mattress begins to adapt to your body.

How Memory Foam Works [Infographic] | Sleep Advisor

What is viscoelasticity?

For example, thick lubricating oil or treacle would be described as viscous, meaning both thick and (reluctantly) runny. Slower flow is caused by a greater amount of viscosity in a given substance. The low viscosity of water makes it flow rapidly, but the high viscosity of honey makes it flow slowly. When something is elastic, it can be stretched or deformed but will always return to its original size and shape after the stretching force has been removed. “Elastic” refers to items that are pliable and able to return to their original shape after being stretched. Rubber or a stretchy plastic of some kind are what we’re really referring to when we say “elastic.”

When we talk about viscoelastic, what exactly do we mean? A viscoelastic substance is both viscous and elastic (it returns to its original shape). For the most part, it deforms and re-forms quite slowly. Simply put, that’s a basic definition of viscoelasticity; the phenomenon is much more nuanced and fascinating. Creep is a material science term for the gradual deformation of a lump of memory foam over a lengthy period of time when a constant force is applied. The way you exert stress on viscoelastic materials alters their behavior. When applied quickly, they become stiffer (change shape more unwillingly) than when applied slowly, making them excellent for absorbing and cushioning shocks. You’ll also notice that a viscoelastic material will take a long time to return to its original shape after you deform it (a typical memory-foam mattress takes 5–10 seconds after getting off it to flex back to shape—much longer than a foam sponge). During the time lag, energy is efficiently absorbed and dissipated (a phenomenon known as hysteresis)—akin to the way energy is lost to “rolling resistance” as a bicycle or automobile tire squashes and bends as it turns around. This can be quite beneficial for cushioning items. Alternatively, you could claim that hysteresis is responsible for the foam’s “memory.”

The following are the four primary characteristics of viscoelastic materials:

  1. As long as you apply a consistent strain, they continue to stretch and deform extremely slowly.
  2. The more you stretch or distort it, the less force you need to maintain the same degree of stretch.
  3. Force-dependent: They stretch more when you apply a force slowly as opposed to quickly.
  4. Material returns to its original shape after a period of stretching, however you don’t receive all of your energy back.

What sorts of materials are viscoelastic?

Is it possible that you’ve been reading this and thinking viscoelasticity is a strange scientific invention that only exists in labs? Everything from leather to concrete, wood, and stone, which may come as a surprise, are all forms of viscoelastic to varying degrees. Viscoelastic properties are also found in body tissue. Poking your stomach or thigh or even the thin cheek of your open lips with a finger will reveal that it takes time to return to its original shape. For the time being, we must use synthetic materials, such as plastic, to make things like bed mattresses. Foam containing 15–75 percent polyether polyol and isocyanate chemicals is used to make viscoelastic foams (any less than 15 percent and the foam does not exhibit substantial viscoelasticity).) foam. Covestro’s Softcel VE-1100 viscoelastic memory foam is among the most common (formerly Bayer MaterialScience)

Why does memory foam get softer as it gets hotter?

A thick substance like treacle becomes much more watery when heated (less viscous). As a result, it should come as no surprise that memory foam’s viscosity changes with temperature. There is a decrease in viscosity as the temperature rises. With regard to VE-1100, its viscosity at room temperature of 20 degrees Celsius (68 degrees Fahrenheit) is around 280 cSt (centistokes), but at body temperature (37 degrees Celsius or 96.6 degrees Fahrenheit), it drops to about 150 cSt. It’s for this reason that a memory foam mattress may become noticeably squishier after a few hours of use that it becomes more flexible as it cools. A similar result can be achieved by increasing the relative humidity of the air.

Ordinary memory foam is unable to dissipate heat or moisture since the foam is not ventilated in any way. Because you’ll be lying on it for up to eight hours at a time when you sleep, this can be a major issue. Several memory foams are formed of reticulated foam, which has a more open-celled structure that improves ventilation and allows moisture to drain away from the body.

Is memory foam more hygienic?

Additionally, high-density foam mattresses are said to be cleaner because bedbugs don’t seem to enjoy dwelling in the material. It’s not quite accurate to say that your bedroom is completely free of bugs, as they can be found in your bedding, on your carpet, on your walls, and in many other places. Memory foam beds may lessen the problem of bedbugs, but a strict hygiene regimen is the only effective remedy, not just a mattress change. Some memory foams, on the other hand, include antibacterial agents and deodorants in the polymer mix in order to improve the product’s hygiene.

Viscoelasticity in everyday life

Memory foam isn’t just for mattresses and pillows; it has a wide range of other applications. An earplug set, including some made of memory foam, came packaged with my most recent purchase of noise-canceling headphones. You put them in your ear canals and, over time, they begin to relax, forming a seal around your eardrums and preventing undesired sounds from entering your ears.

Foam earplugs (also known as ear defenders) of higher quality are often manufactured from memory foam, so keep that in mind when inserting them into your ears. After around 30–60 seconds, with your finger pressed loosely on the end, you’ll notice that they expand, stay in your ears, and seal considerably better than if you immediately push them in and withdraw your finger. Why? In part, this is due to the fact that they’re viscoelastic, which means we may take advantage of the delay in deformation and relaxation that they exhibit.

The term “viscoelasticity” is frequently heard in the medical community. Viscoelasticity is also a property of hydrocolloidal wound-care dressings, such as pressure-relieving cushions, as well as simple objects like pillows (used in blister plasters). The eye surgeon, prosthetist, or someone working on producing artificial skin that mimics the skin’s natural properties should all be familiar with viscoelasticity. Viscoelastic gels are used to preserve and stabilize eye structures during procedures such as cataract and glaucoma surgery.

NASA launched the Challenger Space Shuttle on January 28, 1986, and viscoelasticity made headlines for the first time in its history. When rubbery materials are used for fluid seals and gaskets, they tend to be viscoelastic, which means they fit snugly and seal efficiently. For one thing, this implies that the way they fit and seal can be drastically altered by the temperature at which they are being used. That that day, the O-ring seals in the Shuttle’s twin solid rocket boosters could not flex and seal properly due to the extreme cold. An explosion in the gasoline tanks caused Challenger to detonate, killing all seven people on board.

How to Pick The Right Memory Foam Mattress?

If you’ve made up your mind that memory foam is the appropriate material for you, there are a few things you should keep in mind as you begin your search for the perfect mattress made of memory foam. The following are some general guidelines for selecting a memory foam mattress.


The firmness of a mattress can vary greatly. Many mattresses are described in terms of their firmness, which can be broken down numerically from 1 (extremely soft) up to 10 (very firm) (very firm). Some individuals prefer their beds to be extremely hard, while others prefer them to be extremely soft, so this is a more complex version of the story of Goldilocks and the Three Bears.

Soft-firm mattresses are the most common type of mattress sold in stores and online. You can also seek for an Indentation Load Deflection (ILD) rating if that information isn’t available or isn’t thorough enough. Basically, the greater the ILD rating is, the firmer you may expect the mattress to feel. Every layer of the mattress (such as the comfort, transition, and support layers) has an ILD score, and the mattress as a whole is given an ILD overall score. A mattress with an ILD of 10 is considered to be extremely soft, whilst a mattress with an ILD of 50 is considered to be extremely hard. If you’re looking for something in the middle, use those criteria.


The amount of actual foam in each layer of memory foam is what determines the mattress’ density. Different densities of memory foam are measured in pounds per cubic foot (lb/cu ft) (PCF). If you’re looking for a long-lasting foam, you’ll want to go for a density that’s higher than average. Higher-density foams, on the other hand, tend to be warmer to sleep on.

When it comes to density, 3.0-5.0 PFC is ideal for those who sleep at an average temperature (i.e., they don’t sleep excessively hot).


The thickness of a memory foam mattress is measured in inches from the long side. This is not the same as density: a three-inch piece of foam could have an ILD of 10 or 50, for example. The thickness of a memory foam mattress can range anywhere from 6 inches to 14 inches. If you’re looking for a supporting mattress, a thicker mattress is usually better than one that’s thinner. However, this isn’t always the case.

What is Memory Foam - A Look at The Pros and Cons - The Sleep Judge

In addition to the thickness of the mattress as a whole, you should also consider the thickness of each individual level. Memory foam mattresses work best if there are at least four inches of combined comfort and transition foam between the sleep surface and the mattress base. This helps ensure that you will get the benefits of the support core without the mattress becoming uncomfortable.

Consider the total thickness of the mattress and the thickness of each layer separately. Comfort and transition foams should be at least four inches thick between the sleep surface of the mattress and its foundation. As a result, you’re more likely to reap the benefits of the support core without experiencing any discomfort from the mattress itself.

In addition to the overall thickness of the mattress, you need also take into account the thickness of each level. Comfort and transition foams should be at least four inches thick between the sleep surface of the mattress and its base. Having a supportive core without an uncomfortable mattress is important, therefore this is one way to achieve that goal.

Mercury, lead, heavy metals, or formaldehyde are not permitted in the production of a Certipur-US certified mattress. Phthalates (plasticizers that may impair reproductive health) and PBDEs are not utilized in their production (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). These certified mattresses also have a lower concentration of volatile organic compounds (VOCs), which are the main cause of the chemical smell that comes from off-gassing.

As far as safety and quality go, a mattress with certified foam means that you have one less thing to worry about when it comes to choosing the right mattress for you.

What’s So Special About Memory Foam?

Memory foam’s unique ability to mold to your body’s contours is what makes it so fantastic. Conventional mattresses frequently fail to provide adequate general support for the body as well as adequate relief for the numerous pressure points on which we sleep.

Over time, a lack of proper support can lead to discomfort in places such as the elbows and hips, which are unpleasant to lie on for a long amount of time. Memory foam provides supple support and wraps around you for superior, more personalised support by cushioning your entire body.

Memory foam mattresses, in contrast to traditional spring mattresses, are responsive to even the smallest changes in pressure. The viscoelastic material, a mix of viscous and elastic, is what actually determines the memory foam design; it changes shape when a sufficient force is applied, gradually reverting to its previous shape when compression is released. In addition to being a temperature sensitive material, the foam is ideal for use with the human body.

What is Memory Foam? | Sleep Foundation

Why Is Memory Foam Good For You?

A good traditional mattress may have a few hundred springs under you, but memory foam is like having a million tiny springs working together to suit your body. #1 Memory foam.

Because of the fluid-like response on your body, a memory mattress provides a better night’s sleep than a traditional mattress because of its ability to alleviate pressure points caused by movement during sleep.

In addition, memory foam has a unique ability to mold itself to your body.

Do you have trouble falling asleep at night? Memory foam mattresses, in contrast to spring mattresses, allow you to move around freely while sleeping without disturbing your companion.

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