By: Blonde Two

If you have ever tried camping without any kind of sleeping mat, you will know that the ground is a cold place to be. Even camping in this summer’s heat, you would feel the chill through your sleeping bag if you choose to place it straight onto a ground sheet. When I was a Girl Guide, my sleeping roll had double the layers of blankets underneath me as it did on top for this very reason. Sleeping mats, however, have progressed a long way since then (see tomorrow’s Tuesday’s Ten) and, these days, can represent a considerable financial investment. There are many factors that can influence your choice of sleeping mat including weight, comfort, size and acoustics (some of the lighter weight ones are noisy) but one factor that is maybe less understood is the warmth or R-value of a sleeping mat.

What does R-value mean?

There is a sensible answer to this question but, if you didn’t know better, you could imagine that R-value might give you a myriad of other parameters with which to measure your prospective sleeping mat.

R-value = Roll Value

A sleeping mat that could deal with any angles of slope that you cared to throw at it… a guarantee that you wouldn’t roll off in the middle of the night.

R-value = Relish Value

A sleeping mat that you could eat and which actually tasted good… on a cold night that would be worth every ounce of its weight.

R-value = Romance Value

Imagine a sleeping mat that enhanced your ability to attract a mate… sales would go through the roof.

R-value = Rustle Value

Some of the lighter weight inflatable sleeping mats are well known for sounding like noisy crisp packets in the middle of the night… probably ok for you but maybe not for your tent-mates.

The real meaning of R-value

However (be sensible Blonde Two) R-value actually refers to thermal resistance, in other words, the insulating properties of a product (in this case sleeping mat but another example would be wall insulation). If a sleeping mat has a high R-value, it will insulate better. For example a sleeping mat with an R-value of 5 would be suitable for 4-season camping and a sleeping mat with an R-value of 2 or below really only suitable for summer. Some manufacturers choose to test R-value but the methods of doing so haven’t been standardised so it pays to chat to other people who do the same type of camping as you do before making your choice.

Do I need to spend lots of money to get a warm sleeping mat?

This is a tricky one and it pays to remember that your good night’s sleep relies on comfort as well as warmth (although obviously the two go together). Believe it or not, some of the old fashioned foam mats have a better R-value than some of the new inflatable ones but they are obviously not going to be as accommodating when you turn over in the middle of the night and are prone to squashing, which can reduce both comfort and warmth. I carry a half foam mat on the back of my rucksack, ostensibly for emergency purposes to keep a casualty warm but, in reality, it is more often used to sit on when I have a cup of tea. However I do know that with my bivvy bag (or orange survival bag), my spare clothing and that half foam mat, I could spend a reasonable night out on the hills should I need to.

We hope that has given you enough information about R-value to feel like you can go out and choose a sleeping mat to suit you. Just remember that warmth isn’t the only factor and that a sleeping mat isn’t the only way you can add warmth to your sleep. Don’t be afraid, when you go shopping, to ask staff for advice about what is most suitable for the type of camping you are planning to do.