Memory Foam Mattresses - A Guide

About memory foam

When you lie on memory foam, it moulds to your body's shape such that every point of your body is in contact with its surface and receives equal support. This reduces the discomfort of pressure build-up on particular parts of the body that can occur with conventional mattresses.

Rather than springing back when your weight is removed, memory foam retains an indentation and slowly returns to its original shape. Downward pressure is absorbed and redistributed across its surface, ensuring your whole body is supported. This is what makes it a uniquely comfortable sleeping surface.

(For more information on the properties of memory foam, see What is Memory Foam?).

Memory foam mattress types

Since they were first introduced by Swedish company Tempur-Pedic, memory foam mattresses have become available from a number of manufacturers in a number of varieties, depending on your needs and price range. While the quality of the memory foam itself is very important, the quality and type of the mattress core is integral to ensuring the unique advantages of the memory foam are properly supported.

Memory foam alone would allow you to sink right down into it, so a suitable supportive core with the right level of spring-back is necessary to counteract the gravitational force of your body. A good quality mattress core will provide the right amount of supporting upward pressure that can be absorbed by the memory foam layer without exerting upward pressure on your body and counteracting the pressure relieving properties of the memory foam.

Fully foam mattress

These mattresses are made entirely from foam. They typically have a firm, supportive foam at the core with a layer of memory foam bonded above this.

Combined foam and inner-spring mattress

These mattresses use a traditional spring unit as a mattress core, rather than polyurethane foam.

Memory foam mattress toppers

A memory foam topper or pad can be added to your existing mattress to provide an extra layer of comfort. This is a cost-effective way to get the benefits of memory foam and transform your bed, provided your existing mattress is of sufficient quality and is free of lumps or hollows.

If you're looking for a double or larger mattress for two people and prefer a softer or firmer bed than your partner, then a split-firmness mattress is a good compromise. These have memory foam of different firmness and density on either half of the mattress to meet the preferences of either partner. Split adjustable-bed memory foam mattresses are also available for couples with adjustable beds with separately adjustable sides.

Determining memory foam quality

Good quality memory foam can still be quite expensive, but a cheaper alternative won't provide the same comfort and won't last very long – remember that when spread over the many years of your memory foam mattress's life, the initial expense is well worth the investment.

While no single measurement will unequivocally decide the quality of a memory foam mattress, there are some basic factors that can be taken into account when shopping for one. These factors should be considered together when you compare memory foam beds, and not in isolation. You should also consider your body weight when deciding what level of support you need - many mattresses are available in different types that are tailored to different body weights.

Density

First, memory foam should have a high density. It is the addition of density-increasing chemicals that distinguishes it from ordinary foam and gives it its unique properties. Higher density memory foams are better at absorbing pressure - and thereby exemplify the comfort benefits of memory foam – and will continue to return to their original shape for a lot longer than cheaper, low-density equivalents.

Higher density foam naturally requires more raw materials and is therefore more expensive, however there are many advantages that out-weigh this additional cost:

• It provides more cushioning and support, conforming more precisely to your body shape.
• It reacts to temperature, not pressure. High density foam will mould to your body by softening in reaction to your body heat and not as a result of pressure, as a lower density foam would. This makes it generally more supportive.
• You won't sink through - higher density foam won't allow you to sink through to the mattress core, which would reduce the benefit of the memory foam layer.

Memory foam densities typically range from about 2.5 lb/cubic ft to 5.3 lb/cubic ft (40kg/m³ to 85kg/m³). Below are some typical memory foam densities and specific examples:

Typical Foam Densities

Specific Examples

Firmness

Firmness is usually measured by determining the amount of pressure required to make a 1 inch indentation in the mattress over a certain area; this measure is known as the IFD (Indentation Force Deflection). However, memory foam is too soft a material from which to make a whole mattress – it would engulf the sleeper - so this measure should not be assumed to represent the firmness of a mattress as a whole.

The support of a mattress is provided by the mattress core and not by the memory foam layer. However, memory foam should be firm enough to keep you above the mattress core, or it will lose its benefits.

Thickness

The thickness of the memory foam layer on a mattress can also be an important factor. If this layer is too thin, then you can sink right down to the core of the mattress and lose the benefits of the memory foam layer. This should be taken into account in conjunction with the firmness – even a very thick memory foam layer could allow you to sink right through to the mattress core if it is very soft.

The cloud of facts and figures around memory foam may make shopping for memory foam mattresses seem a daunting task, but with a few simple enquiries and a little preparation you can make an informed decision about which memory foam mattress will best suit you. When you know you're getting a good quality memory foam mattress that will last for years, you'll be glad of the time spent.