What is a Memory Foam Mattress? [2024 Guide]

What is a Memory Foam Mattress?

What is a Memory Foam Mattress?

A memory foam mattress is a type of mattress consisting of a layer of springs with a layer of temperature sensitive ’memory foam’ on top. Memory foam reacts to the pressure and heat from your body, evenly distributing body weight and changing shape to fit the contours of the sleeper.

Viscoelastic (memory foam) has slow moving properties, when pressure is applied to the material and released, viscoelastic, or memory foam, remains in the shape for a few seconds before springing back up, it ‘remembers’ its original shape. 



As a result of viscoelastic properties, a memory foam mattress reacts to the pressure and heat from your body, evenly distributing body weight and changing shape to fit the contours of the sleeper. This results in the 'hug' effect that advocates of memory foam mattresses appreciate. When the pressure and body heat of its occupant is removed, memory foam then returns to its original shape.

As a detailed extension to our Mattress Buying Guide, we look at some of the key features of memory foam mattresses.


Types of Memory Foam

Memory foam has evolved with time leading to new generations of foam which are adept at fighting heat retention—traditional memory foam’s common complaint.


Traditional memory foam entered the market in the 1990s and revolutionised mattresses at the time. Designed to support and decrease stress on joints and pressure points its main flaw was, and is, that it can cause discomfort due to excessive heat retention.

Open Cell

Open Cell memory foam was designed to address the common complaint that traditional memory foam caused excessive heat retention i.e. it was "too warm". Air flow is facilitated by millions of balloon/sphere shaped cells within the mattress, air passes around these which helps with the quick removal of body heat.

Gel Infused

Gel infused memory foam has added cooling gel or gel beads. This enhances the coolness of the mattress because the gel beads comprise “phase-changing material” or “PCM”, which absorbs heat—helping the bed stay cool.


Plant -based memory foam replaces a portion of the petrochemical content with natural plant based oils. As a result of this these mattresses are often cooler than their non plant-based equivalents.

Memory Foam Density

Memory foam comes in a variety of different densities which can be very confusing for the first time buyer. As a rule of thumb,: the  higher the density, the firmer, more supportive and (usually) more expensive the mattress.

Memory foam density density is measured in kilograms per cubic metre, although it's often expressed simply as, just the number e.g. "45kg": this means a cubic metre of the foam weighs 45 kilograms. 

The table below gives an overview of density and corresponding “firmness”

Density Firmness







70kg or higher

Firm - Extra Firm


Which density is right for me?

As with every type of mattress, this is a very personal decision, however the following pointers should help your decision:

  • Lower-density mattresses tend to lose their shape and elasticity more quickly
  • Higher densities will offer more support. 
  • Heavier people, or people with back and joint problems, will be better served by higher densities of memory foam.


What are the benefits of a memory foam mattress?

1) Fits to the body

Thanks to its slow moving properties, mattresses made from memory foam shape themselves around the body in response to the pressure and heat of the individual, evenly supporting body weight when occupied and returning to its original state when the pressure is removed. 


2) Adjusts to temperature

The temperature of your body can impact how well you sleep at night. The temperature sensitive nature of memory foam means that as your body temperature increases, the mattress softens, offering a more comfortable sleep. For those who tend to have a higher temperature which affects sleep, memory foam mattresses with cooling technology ensure you don’t become overheated.


3) Provides relief for aches and pains

Memory foam material’s ability to displace pressure from points of pain around the body and offer a moulded support helps by relieving pressure on body aches and pain points. With its ability to adjust in reaction to temperature, memory foam can mould itself in reaction to areas of the body where pain may represent as a slightly higher temperature and can add or reduce pressure to the area.


4) Allergy Friendly

Composed of a polyurethane foam, which has a dense composition and is made of fibres which prevent the collection of allergy-causing mites, memory foam mattresses accumulate less allergens over time.


5) Provides a stable sleep foundation

With memory foam moulding itself around each individual body on a mattress, catering to each body’s unique needs. In turn, tossing and turning is less likely which reduces motion transfer throughout the bed, ensuring a good nights sleep for all its occupants.

Sleep needs and preferences vary from person-to-person, and memory foam beds offer an alternative to a regular mattress. With such a wide range of memory and hybrid memory foam mattresses available on the Irish market, there’s a choice there for everyone.


Memory Foam Pros

  • Allergy friendly: made from materials that are resistant to allergens
  • Pain relief: moulded support helps by relieving pressure on body aches and pain points
  • Reduces restlessness: Tossing & turning less likely due to mattress ‘moulding’ to sleepers contours.

Memory Foam Cons

  • Too hot: many find that even cooling memory foam mattresses leave them too warm.
  • Chemicals: some “traditional” style memory foam is created using petrochemicals.
  • Heavy: mattresses made exclusively from memory foam tend to be much heavier than their sprung equivalents


Memory foam mattresses are an excellent choice for those that prefer a firmer, more supportive sleeping surface, particularly those that suffer from back problems. Despite this, due to overheating and the classic memory foam 'hugging' effect, memory foam is not for everyone. 

Mattress Type FAQs

What is a hybrid mattress?

What is an orthopaedic mattress?

What is a pocket sprung mattress?

What is a pillow top mattress?

What is a coil sprung mattress?

Further Reading

To learn more about choosing a mattress, our guide Choosing the best mattress explains the different types of mattress and how to choose the right one for your specific needs

Brian McCann

Our Managing Director Brian's expertise in crafting comfortable sleep experiences makes him a reliable voice for all things bedding-related. Brian publishes advice and tips on mattresses, beds and the overall sleep experience based on extensive industry experience.

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