If you’ve been exploring the world of mattresses recently, there’s a good chance you’ve come across the term “memory foam.” Mattresses come in various styles and materials, but memory foam has surged in popularity.
Originally developed in the 1960s for use in NASA spaceship seats and seatbelts, memory foam has also found its way into helmets, shoes, prosthetics, and wheelchair seating pads as a shock-absorbing and pressure-relieving material. However, it wasn’t until the 1990s, when Fagerdella World Foams introduced their flagship TempurPedic Swedish mattress, that memory foam made its mark in the mattress industry. Since then, memory foam mattresses have taken off, especially with the rise of mattress-in-a-box brands.
But what exactly is memory foam? What is it composed of, how does it function, and how can you determine if it’s the right choice for you?
Rest assured, we have you fully covered. In this comprehensive guide to everything you need to know about memory foam, we will delve into the intricacies of this material, its applications in mattresses, and the key factors to consider as an informed mattress shopper.
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Now, let’s start at the beginning. What is memory foam in physical terms?
The primary component of memory foam is a polymer called polyurethane. This polymer, with its large molecules consisting of bonded subunits, is used ubiquitously in various plastic products. Beyond furniture like sofas and mattresses, polyurethane is employed in insulation, liquid paints and primers, spray foam, elastic fibers, car parts, and even resilient elastomers like roller blade wheels.
Memory foam, specifically, is a type of polyurethane foam known as “viscoelastic” foam or low-resistance polyurethane foam (LRPu). By adding different compounds and additives to polyurethane, memory foam is produced in distinct variations.
These chemical components significantly impact two fundamental characteristics of memory foam: its viscosity and elasticity. In the context of memory foam, “viscous” means the material takes a considerable amount of time to change shape under pressure or transfer energy. On the other hand, “elastic” refers to the material’s ability to stretch or deform and then return to its original shape or size after the stretching force is removed.
Different manufacturers employ their own unique chemical formulas and processes for creating memory foam. These formulas and processes influence the feel and functionality of each memory foam product and are often closely guarded secrets. However, polyether polyol, a compound that enhances both elasticity and viscosity, is typically present in most memory foam mattresses.
As mentioned earlier, memory foam mattresses are designed to gradually conform to the body, evenly distributing body weight and providing support. They are resilient, able to bounce back to their original shape when pressure is alleviated.
When memory foam comes into contact with body heat, it softens and molds to the unique contours of the individual. This allows for equal weight distribution. Notably, memory foam responds differently depending on the force applied. If pressure is applied rapidly, the foam tends to change shape more slowly—an effect referred to as “reluctant.” This unique property makes memory foam exceptional at absorbing the impact force, which initially made it suitable for space shuttle construction. As a mattress material, this quality ensures the body is comfortably cushioned and allows for a gradual contouring experience as the mattress adapts to the body’s impact and takes the form of its curves.
Additionally, memory foam takes a relatively long time—around 5-10 seconds—to return to its original shape when pressure is released. During this recovery phase, the energy from the impact is absorbed and dissipated. This delay in recoiling, known as “hysteresis,” contributes to the cushioning effect for sleepers, reducing pressure generated by the body while lying down.
Another significant aspect of memory foam’s functionality is its temperature-dependent viscosity. As the temperature increases, the viscosity decreases, causing the foam to become less rigid and more flexible. This is why memory foam mattresses feel softer and more pliable after some time spent lying on them, as body heat raises the temperature of the sleep surface.
Memory foam mattresses are available in a vast array of sizes, shapes, and construction styles. Beyond the proprietary variations in compounds and processes associated with each individual foam product, there are several fundamental categories of memory foam.
By and large, there exist three primary classifications of memory foam:
Conventional
This represents the authentic, “time-honored” memory foam. It was the pioneering form of memory foam to enter the market for consumer use. Conventional memory foam is engineered to conform to your body and is constructed in the manner we have previously outlined. One drawback of conventional memory foam is its tendency to retain heat, which can result in the sleeping surface of mattresses employing this foam becoming uncomfortably warm. The creation of the other two types of memory foam was in part meant to address this issue.
Open-Cell
Open-cell memory foam contains the same ingredients as conventional memory foam but possesses a distinct internal structure. Open-cell memory foam mattresses encompass internal pockets, known as “open cells,” which allow for ventilation and airflow throughout the mattress, thereby facilitating heat dispersion.
Initially, open-cell memory foam mattresses were less dense, which occasionally affected their firmness and rendered them less supportive. However, innovative production techniques have been developed to tackle this issue while preserving the open-cell structure (and consequently retaining the cooling effect).
Gel
Another variant of memory foam incorporates gel into its composition. Typically, gels are infused into the foam by injecting gel-based microbeads. These microbeads create pockets similar to those found in open-cell mattresses. Instead of merely allowing air to pass through the mattress, these gels function as “phase-changing” materials, actively absorbing and releasing heat generated by your body.
Certain mattresses adhere to foams that strictly align with one of these categories, but many modern memory foam mattresses incorporate elements from all three.
In addition to these three primary types, some memory foam mattress manufacturers have begun incorporating other materials into their products, often with the specific goal of enhancing cooling properties. One such material is copper. Copper possesses remarkable conductivity and aids in both heat dispersion and moisture wicking when utilized in memory foam mattresses. Mattresses that combine the three main types of memory foam with copper in their composition are readily available.
Yet another innovation on the horizon within the realm of memory foam is the development of eco-friendly foams. These environmentally conscious memory foams, known as “greener memory foams,” incorporate a higher proportion of plant-based materials than the average memory foam mattress. For example, they may replace some of the petroleum-based compounds and derivatives commonly employed in standard memory foam production with compounds and derivatives derived from soy or corn oil. While these manufacturing techniques are still relatively novel, they are becoming increasingly prevalent as the technology advances.
Memory foam is employed in various ways within mattresses. Different memory foam mattresses possess distinct constructions designed to achieve specific qualities. Nevertheless, most memory foam mattresses adhere to a fundamental template, despite variations in unique components. This template consists of three components:
Now that we have comprehended the true nature of memory foam, we can delve into how it feels and what sleeping on a memory foam mattress entails. Generally speaking, memory foam mattresses possess three core characteristics, although the specific levels of these features may vary across different mattresses:
- Conforming: One of the distinguishing attributes of memory foam resides in its ability to conform to the contours and angles of your body when you recline on the mattress.
- Sinking Sensation: Apart from its contouring ability, memory foam tends to produce a unique sensation of “sinking” into the mattress, as if it’s embracing your body and pulling you down.
- Tangible Response: As previously mentioned, memory foam is highly responsive to pressure. When you lie down, you can physically feel the material becoming more pliable and less sticky in response to the heat and pressure from your body.
Additionally, memory foam mattresses possess various specific characteristics that elicit both adoration and aversion among individuals. While many people adore the adaptive feel of memory foam, it is not universally suitable, and some individuals find it uncomfortable. Disadvantages of memory foam mattresses may include excessive softness, inadequate temperature regulation, and a potent initial off-gassing smell.
Therefore, it is crucial to address the commonly reported benefits and complaints when discussing memory foam.
Pressure Relief: Memory foam molds to the contours of your body, utilizing your body heat and pressure to conform to your unique shape. This provides relief in areas that experience the most pressure during sleep, such as the hips, shoulders, and neck. Exerting irregular and disproportionate pressure on these body parts can lead to morning pain, as well as difficulties falling and staying asleep.
For individuals with joint pain or arthritis, memory foam’s contouring properties can alleviate discomfort and reduce pain by evenly distributing weight and relieving pressure from common stress points.
Promotes Spinal Alignment: Another advantage of memory foam’s contouring properties is that it promotes proper spinal alignment and offers lumbar support for many sleepers. When a sleep surface responds to the body’s natural curves like memory foam does, it becomes easier to find sleeping positions that maintain neutral spine alignment. This can prevent nighttime restlessness, as well as back pain and morning soreness.
Allergy Resistance: A notable benefit of memory foam mattresses is their tendency to resist the accumulation of common allergens for individuals with allergies. Due to their dense structure, memory foam mattresses are less likely to attract and gather allergens like dust mites, mold, and other irritants.
Reduced Motion Transfer: Those who sleep with a partner, particularly light sleepers, prioritize a mattress that minimizes the impact of their partner’s movements or nocturnal activities.
If you value motion isolation, memory foam offers a significant advantage. Its density and ability to distribute pressure effectively keep motion confined to the specific area of the bed, preventing it from transferring to other parts.
Noiseless: One remarkable characteristic of memory foam mattresses is their ability to operate silently. This is especially important for couples who want to prevent disruptions when getting out of bed. It is also beneficial for individuals who prefer to avoid the disturbances caused by squeaks, groans, or other noises associated with a noisy sleep surface.
Heat Retention: One of the primary grievances concerning memory foam mattresses is their tendency to retain heat, resulting in discomfort and warmth. Due to their responsiveness to body heat and their material’s density, memory foam mattresses can become quite warm, especially traditional memory foam.
Although advancements in memory foam technology, such as open-cell and gel foams, and other cooling construction methods, have been introduced to address this issue, memory foam still retains more heat compared to other mattress types. This can hinder sleep onset and maintenance, particularly for individuals who already experience heightened warmth during sleep.
Cost: Another aspect of memory foam to consider is its relatively higher price compared to other mattresses. This is especially evident when comparing a high-quality memory foam mattress to a similar-quality innerspring mattress, as memory foam mattresses usually come with a steeper price tag.
As memory foam mattresses gain wider popularity, especially with the rise of mattress-in-a-box companies, the overall cost of memory foam mattresses has declined. Nonetheless, they generally remain the pricier option.
Not Waterproof: Memory foam mattresses, including memory foam toppers and pillows, are susceptible to damage from water and moisture. Exposure to liquid can degrade the foam and shorten the lifespan of the mattress. This can be especially problematic for those living in high-humidity areas or with young children or pets prone to spills or accidents. Additionally, cleaning a memory foam mattress can be challenging.
Feeling of Being “Stuck”: Some individuals may find that the sinking feeling associated with memory foam mattresses makes them feel trapped or engulfed by the material. This can hinder movement during the night and cause discomfort. Over time, the sinkage tends to increase, intensifying the feeling of being stuck.
Off-Gassing and Odors: Initially, memory foam mattresses often emit a distinct chemical odor called “off-gassing.” Generally, this smell dissipates within 24 hours after unpacking, but in some cases, it can linger for weeks. Memory foam mattresses made with cheaper materials may have stronger and longer-lasting off-gassing.
Heavy and Challenging to Move: Despite the perception of being lightweight due to the mattress-in-a-box concept, memory foam mattresses are typically heavier than other mattress types. This can create difficulties when changing sheets or adjusting the mattress’s position. Moving a memory foam mattress, especially one in a box, can be particularly challenging and require more effort than initially bringing it into a room.
If you have determined that a memory foam mattress is right for you, it is essential to consider several factors when searching for the perfect match.
Firmness
Mattresses vary in terms of firmness, which is often categorized on a scale ranging from very soft to very firm. Different individuals prefer mattresses with varying degrees of firmness, some favoring very firm mattresses, others desiring a softer feel, and some seeking a middle-ground option.
Most mattress descriptions will provide information on where they fall on the soft-firm scale. If this information is not readily available or lacks detail, you can look for an Indentation Load Deflection (ILD) rating. ILD measures the mattress’s overall firmness, with higher ratings indicating a firmer feel. Each layer of the mattress also possesses its own ILD score, contributing to the overall feel. For example, a mattress with an ILD score of 10 would be very soft, while a mattress with an ILD of 50 would be considered very firm. This provides a reference point for selecting a middle-ground firmness level.
Density
Memory foam density refers to the amount of foam present in each mattress layer, measured in pounds per cubic foot (PCF). Higher density foams generally retain their shape, elasticity, and support structures for a longer period. However, they tend to retain more heat.
For average-temperature sleepers, a density between 3.0-5.0 PCF strikes a balance between longevity and heat retention.
Thickness
When discussing memory foam mattresses, thickness refers to the measurement in inches from the mattress’s side. This should not be confused with density. For example, a three-inch layer of foam can have an ILD score of 10 or 50. Memory foam mattresses range in thickness from approximately 6 inches to 14 inches. Generally, thicker mattresses offer more support and can also provide a softer feel, depending on the specific mattress.
When considering the overall thickness of a mattress, it is important to also take into account the thickness of each individual layer. For optimal performance, memory foam mattresses should have a minimum of four inches of combined comfort and transition foam between the sleep surface and the mattress base. This ensures that you receive the benefits of the support core while avoiding any discomfort.
Quality Assurance for Testing Standards
Lower quality memory foam mattresses may contain additives that can compromise the material, shorten the lifespan of the mattress, and potentially cause irritation or emit questionable fumes. When selecting your mattress, it is crucial to look for the Certipur-US certification. This certification guarantees that the memory foam used in the mattress is manufactured without certain chemicals that can be detrimental to both the mattress and your health.
A mattress with Certipur-US certification is free from mercury, lead, heavy metals, and formaldehyde. It is also free from phthalates, which are plasticizers that can have harmful effects on reproductive health. Additionally, these certified mattresses do not contain PBDEs (Polybrominated diphenyl ethers), a flame retardant that is banned in the US due to its negative health effects but is sometimes used in mattress production abroad. Moreover, these certified mattresses have lower levels of volatile organic compounds (VOCs), which are responsible for the chemical smell that occurs upon off-gassing.
Choosing a mattress with certified foam provides peace of mind in terms of quality, durability, and safety. Therefore, it is wise to check for certification before making a final decision.
