Types of Sleeping Mat:

Closed Cell Foam:

Often the lightest mats closed cell foam mats provide good insulation but not much comfort - they are tough and can be cut to shape - a big disadvantage is their packed size - which is big - but if you have a large rucksack you can line it with a closed cell foam mat and pack everything else inside it.

Foam mats come in various thicknesses each giving varying comfort and insulation value - Thermarest have taken the foam mat a stage further with the Ridgerest series and the Z-Lite - both of these have a raised patterned surface that increases the comfort of the mat.

Advantages:

Disadvantages:

• Provide only minimal cushioning
• Bulky when packed

Thermarest Z-Lite

Multimat Advance Camp Ice Mat 14 XXL Closed Cell Foam Mat

Thermarest Ridgerest

Self Inflating:

These mats consist of an open cell foam body sandwiched between a light nylon face fabric - there is a valve at one end.

They are called self inflating because when you open the valve the foam inside expands sucking in air through the valve. In practice blowing air through the valve is much quicker and you can get more air into the mat this way.

These mats are thicker than closed cell foam mats and are therefore more comfortable - they can be more insulative and compress quite small for packing away.

Advantages:

Disadvantages:

• Can be punctured
• Heavy compared to closed cell foam mats

Nemo Zor Pad

Multimat Adventure Series

Thermarest Prolite Plus Series

Airbeds:

These are arguably the most comfortable mats, they are generally thicker than other types of mat and so support the body more effectively. But they can be heavy and provide very little insulation.

Advantages:

• Very comfortable
• Small packsize

Disadvantages:

• Poor insulation
• Can be punctured - then they are useless - unlike self inflating mats which at least provide some foam and insulation.
• Need blowing up

Multimat Adventure Air

Insulated Airbeds:

A relatively new category - these attempt to overcome the lack of insulation of an airbed whilst still retaining the comfort. Various techniques are used to provide the insulation - foam inserts - filling the airtubes with down etc..

Advantages:

Disadvantages:

• Can be punctured
• Require blowing up

Thermarest NeoAir

Exped Downmat Series

Thermal Resistance - 'R-value'

Thermal resistance is the measurement that indicates a materials ability to insulate - there are a number of different ways to express this but, as they all measure the same factor, they are all related.

The starting point is the R-value. Around most of the world the R-value is expressed in 'SI' units and an R-value of 1 = 1 m2K/Watt. A material is said to have an R-value of 'X' when the temperature difference between the surface is 'X' degrees Celsius when the flow of heat through the material is equal to 1 Watt per square metre.

The exact meaning is perhaps not important when choosing a sleeping mat - its more the relative performance of each mat that you need to know. So all mats with an R-value quoted in SI untis can be compared directly with one another.

Some of our manufacturers quote insulation value using a 'TOG' rating - more commonly found to rate duvets a TOG of 12-14 is thought to be typical for a duvet suitable for winter us. For our purposes we need a conversin to the R-value expressed in SI units.

Happily the TOG value is based on the R-value and the conversion is that:

1 TOG = 0.1 R(SI) = 0.1 m2K/Watt

So a mat with a tog rating of 3 with have an R-value (SI) of 0.3

US methods

In the US R-values are expressed using imperial units of ft2F/Btu. The conversion is less neat than a TOG but still straightforward:

1 R-value (US) = 0.17622 R-value (SI)

Thus US quoted R-values are more than 5 times higher than the SI unit version.

Our Standard Approach

In order to compare mats with each other we have converted all manufacturers figures to the R-value (SI). Thus a typical low insulation mat will have an R-value of around 0.3, whereas the highly insulative Exped Downmats have values up to 1.4.