Choosing your sleeping pad
“A good laugh and a long sleep are the two best cures for anything.” Irish proverb
Selecting a sleeping pad is an important choice – it’s the main thing that will keep you comfortable and warm during the night. When you lie directly on the ground, heat is transferred away from your body to the ground quickly because the ground is normally much colder than your body and very conductive. This means that you will lose body heat and get cold. Sleeping bag insulation only works when it is expanded, so sleeping bags provide essentially no insulation between you and the ground.
You do not ‘lose’ heat as such. Heat is a form of energy that can not be destroyed, but it can be moved or changed into a different form. We tend to ‘lose’ heat from it being transfered from us to something else and this can happen in three main ways.
- Conduction is where heat moves from a hot object to a colder object (or area) by moving directly through material, similar to how electricity travels along a wire. You feel this when laying on a cool rock, parts of your body touching the rock feel cold as the heat moves from you to the rock. This transfer can be slowed by putting an insulator between you and the ground.
- Convection creates circular air currents as warm air rises (eg to the top of the sleeping pad) swapping with cool air at the bottom. This movement of heat can be slowed by creating small air chambers and other barriers to slow or stop this air movement. You can see convection in action in a big way above a campfire with embers been lifted high above the fire.
- Radiation is the transfer of heat as a form of light, radiant heat is the main warmth you mostly feel from a campfire and when in direct sunlight. Most of the heat is in the form of infrared light, so we can’t see it, but it moves the same as light. Radiant heat can be reflected (with a mirror) or absorbed into another material that will then heat up (where it move again by conduction or convection). Shiny silver coverings on sleeping pads can help reflect the radiant heat back to you.
Everyone is different when it comes to preferences for sleeping bags, so make sure to try out a few different pads before making a decision. For those prone to pressure injuries, test out sleeping pad at home first before taking it on a bushwalk to ensure that your skin copes. Similarly, for people with back or neck pain, testing at home can help ensure the best pick for your walk.
Here are some examples of different types of sleeping pads with a comparison between various features.
|Air Pad||Air-filled mattresses that the user manually inflate before use. These tend to be thick and comfortable||Small, lightweight, comfortable, compact. Customisable firmness based on how much air is put in. Can be very good insulator depending on style||Expensive. Can make loud crinkly noises depending on the material used.|
Can be punctured or rip, and therefore a real possibility of leaks.
Not all have great at insulating because of the large open air spaces that circulate cold air directly beneath the user. Some manufacturers add insulation to the mattress to significantly reduce this effect.
|Self-inflating||Self-inflating pads combine the warmth of closed cell foam with the comfort of open cell foam. Cells are covered in an airtight, waterproof material. Users inflate the pad by opening a valve and letting the foam inside expand, sucking in air. You can add extra aid if you want it firmer pad.||Comfortable, compact, excellent insulation. Customisable firmness based on how much air is put in.||More expensive and heavier than closed-cell foam.||$$|
|Closed-cell foam||Made of dense foam that is filled with small closed-cell foam that to reduce conduction and convection, thus retaining heat.||Warm, light and hardy (tend to last a long time). Cells are water-repellent, so mat is waterproof. No need to worry about punctures and can double as a seat around the campfire.||Not as comfortable as thicker pads, stiff and firm. Bulky.||$|
Key features to consider:
This is a lab-obtained value that conveys the insulating properties of the sleeping pad. The higher the number, the better the insulation. Since the measurement is made about the resistance of a sleeping pad to heat transfer, the larger the R-value, the better it is at retaining heat (i.e. good for winter).
Insulation type R-value Lowest temperature poor 2-3 0℃ moderate 3-4 -7℃ good 4-5 -10℃ excellent >5 -18℃
Of course, every person is different and their tolerance to cold will vary with the way they sleep and the sleeping bag they use. The R-values are what the pad can do at it’s extreme and not loaded with a person lying on it (this reduces insulation). Select a pad with an R-value that is higher than you expect to have a comfortable night.
Sleeping pads vary in size by their thickness, width and length. Some bushwalkers prefer three-quarter or half sized lengths to save on weight. Bushwalkers may use clothes or other material to provide padding under their feet with shorter pads, but full-length pads tend to be more comfortable. As a general rule the thicker the pad, the more comfortable and few pressure points.
Even more extreme is the Klymit Inertia X-Lite Short Inflatable Hiking Mattress, with parts of the frame missing:
Some sleeping pads are rectangular, while others are mummy-shaped, following the body’s natural shape. For instance, the Therm-a-Rest™ Women’s ProLite
This has the advantage to save on weight due to less material.
- Surface material
Some sleeping pad surfaces are really slippery, causing your sleeping bag to roll off easily, particularly if you move around a lot in your sleep. Surfaces that are textured tend to have more grip and can provide a more comfortable sleep. Too much grip can then make it hard to move around. Some sleeping bags have pockets to hold the sleeping pad. If you have this design, then you tend to want more slippy pads to make it easier to get in and out.
- Inflation time and chambers
The two factors that affect inflation time are the size of the pad and the type of valve. Some valves transport high airflow, meaning that the pad inflates quickly (far more enjoyable to inflate these pads after a long day on the track!). And of course, a three-quarter pad will be much faster to inflate than a similar full-size model. Some pads are self-inflating, while others need to be inflated by mouth. Orally inflated pads tend to be slow and over time can have mold build up inside the pad. To avoid mold growth, use a dry bag pump, as these not only make inflating pads much faster and easier but the bags can also be used to keep gear dry.
Side rail ‘baffles’ are railings on the side of a pad that make it harder for the user to roll off the pad during sleep.