Sleeping pad functions
The modern sleeping pad has been designed to satisfy a wide range of a particular demands:
- insulation from the cold ground
- lightweight
- small pack size
- protection from pointy rocks, branches, etc.
- sufficient cushioning
As with all high-end products, the ideal universal sleeping pad does not exist. In practice, one is constantly forced to make compromises, choosing certain functions and advantages at the expense of others.
Sleeping pad R-value
Besides providing comfortable padding, a sleeping pad primarily functions as an insulating layer between you and cold ground. Multiple factors influence the amount of insulation a sleeping pad provides: The foundation upon which it is placed, its thickness, its outer material, and the design of the pad’s interior. When choosing a place to sleep, leaves or grass are best since these can trap Air and provide additional insulation. The sleeping pad’s qualities are, of course, important as well and reasonably straightforward. As a general rule, thicker pads are warmer than thin ones. The pad’s surface also influences how much warmth it provides and its durability. Foam, grid-like interior structures of inflatable pads, e.g. the Therm-a-Rest Ridge Rest, provide extra insulation.
A sleeping pad’s R-value measures its insulation, indicating how well the pad conducts heat.
The higher a sleeping pad’s R-value is, the better it will insulate your body from the cold ground below. A good sleeping pad also means better heat retention in your sleeping bag.
Reference points for R-values (Source: Therm-a-Rest):
- R = 1: min. +7 °C; for 3 seasons, warm nights
- R = 2: min. +2 °C; for 3 seasons, temperate nights
- R = 3: min. -5 °C; for 3-4 seasons, cool nights
- R = 4: min. -11 °C; for 4 seasons, suited for winter use
- R = 5: min. -17 °C; for high-alpine winter camping
- R = 6: min. -24 °C; for extended winter camping and expedition use
When you have to carry all your gear, e.g. while backpacking, it pays to find a compromise between the pad’s weight and the comfort it provides, as with ratings for sleeping bags, the R-value is only a guideline; not everyone has the same sensitivity to cold, something one should always bear when choosing a sleeping pad.
Pad types
The sleeping pad market can be roughly divided into foam mats, self-inflating sleeping pads, and air mattresses.
Foam mats
The most basic sleeping pads are made of polyethene (PE) foam. Their durability and insulation largely depend on the quality of foam used; lower-quality foam sleeping pads tend to become compressed with prolonged use, diminishing insulation. Higher-grade models are made of closed-cell PE foam, making them more elastic and, thus, more durable. The two most significant advantages of foam mats are their low production cost and high reliability since they are not susceptible to becoming punctured.
Foam mats are available in different sizes and thicknesses (typically 5-20 mm), depending on how much comfort and insulation one looks for. The mat’s top is sometimes coated with aluminium foil or manufactured with a waffle-like profile for extra warmth. Air trapped between a sleeping bag and the hollow spaces in the waffle profile provides additional insulation.
Self-inflating sleeping pads
Self-inflating sleeping pads are a more advanced version of simple foam mats. One of the leading manufacturers of self-inflating sleeping pads today is Exped
How does a self-inflating sleeping mat work?
When not in use, this type of sleeping pad is tightly rolled to remove the Air and make it more compact. To inflate the pad, one has to open the valve(s) and wait for the foam to expand back to its original size, drawing the Air through the open valves and filling the foam’s pores and hollow spaces. Once the valve is closed, the pad retains its volume, just like an air mattress.
Specialized outdoor air mattresses
Extremely light air-tight membranes are used for air mattresses with an insulating filling, setting them apart from conventional air mattresses (e.g. for floating lakes/rivers or for home use). The air compartments are partially filled with down or microfibre to improve insulation. The filling makes this sleeping pad much warmer than foam mats or self-inflating sleeping pads. Such pads are also highly compact when deflated, as well as lightweight. A pump is integrated into a pad or case to reduce pack weight.
The Swiss brand Exped is one of the leading manufacturers of expedition air mattresses, offering high-end models such as the Exped DownMat XP 7 and SynMat XP 9 (with down and synthetic fillings, respectively).
Even if you take great care, a thorn or other sharp object may puncture your sleeping pad – a vast and (potentially dangerous) nuisance while in the backcountry. For this reason, one should always carry an emergency repair kit while on tour.Usage
Having the right gear can make or break a trip. Though it is ultimately a matter of personal preference, the following guidelines should help you set your priorities when choosing a sleeping pad for a specific use.
Car camping
- comfort comes first
- weight is largely irrelevant
- a lot of insulation is usually not necessary
Recommended pad: A thick – 8cm or even 10cm – self-inflating sleeping pad to ensure your camping vacation is as relaxing as possible.
Backpacking
- weight is paramount since you will be carrying every gram
- size is also an essential factor (your backpack is most likely somewhat smaller than your trunk)
- high insulation is not always necessary; it depends on the region and season
- comfort can be neglected according to personal preference
Recommended pad: A self-inflating sleeping pad, 3.8cm to 5cm thick, or a 7cm-pad filled with additional insulating material for colder conditions.
Which insulation mat for expeditions & co?
Expedition means: There are no guarantees on what to expect. Often it’s the little things that are crucial.
- reliability is paramount
- pack size is necessary but not a deciding factor
- insulation is essential
- weight is highly relevant
- comfort is the lowest priority
- Our recommendation: High-quality foam mats with waffle structure, possibly for a better thermal performance twice. Alternatively: air mattresses are filled with insulation material.
Summary: Buying a sleeping pad
Those who sleep outside, in a camping tent or a hut, need a mattress that insulates against the cold and provides cushioning and sleeping comfort. The R-value indicates how well-protected a mat is. As a rule of thumb, the thicker the mat, the higher the R-value is, and the superiority of the comfort – an increase in weight is also a price increase.
There are differences in the construction of the mats: foam mats are less expensive yet less comfortable. Self-inflating sleeping pads offer good insulation, are versatile, lightweight and relatively small in pack size. Air chamber mats provide the best insulation with the lowest weight and the smallest packing size – but also have a higher price tag. The critical question before selecting an insulation mat is, for what purpose will the mat be mainly in use? This will help your decision-making a lot easier. Happy outdoors!