In all actuality, the big three, could – and maybe should – be the big four, to include the sleeping pad. The sleeping bag provides warmth, but it’s main concern is keeping the cold air from attacking at the top. Since the sleeping bag is crushed beneath you, it is actually useless, and leaving your back side open to the elements. Now this may not be a problem during the warm months, but without any insulation beneath you, you may be surprised at the warm months.
So, there are two many reasons for a sleeping pad, and while comfort comes to mind, I would say insulation is a more serious concern. However, if you are going to lug one around, may as well make it comfortable to use!
So, insulation. The insulation is measured in sleeping pads with R-Values. An R-Value is defined as the measure of a given objects thermal resistance. Basically, how well will the given material block heat from being transferred across the given object to the other side. The R-Value is affected by two things, the actual material and the amount of that material. Naturally, the lower the R-Value, the less amount of heat it will resist, so more heat will be lost and you will end up getting colder easier, so obviously, the higher the R-Value the more heat resisted and the warmer you stay. (Just as an example, according to Wikipedia, a brick has an R-Value of 0.2 and snow has an R-Value of 1. And from other random sources, typical insulation in the attics of most US homes are around R 25 – 30, and the insulation in the walls are typically R 15. There is lots to be studied on R-Values, so check it out, it’s rather interesting.)
So, for some bases:
- Therm-A-Rest Z Lite: R 2.2
- Therm-A-Rest Ridge Rest: R 2.6
- REI Lite-Core 1.5 / Therm-A-Rest ProLite: R 3.2
- Big Agnes Insulated Air Core: R 4.1
- Exped Synmat 7: R 4.9
- Exped Downmat 7: R 5.9
- Exped Downmat 9: R 8
These are just a few examples. And while some of these pads are similar, a lot of them are different thicknesses, use different types of insulation, and provide different levels of comfort.
Another thing to look into is the cut. Again, just like sleeping bags, the ones that are smaller and / or cut at the corners (mummy-cut) will weigh less. Typically the pads are offered at 48, 60, and 72 inches. There are other lengths available, depending on the pads. Also, there are typically two widths, 20 and 25 inches. The 20 inch wide pads are probably more common, just because they weigh less than the 25 inch pads. I have found that my arms typically fall off the edges of a 20 inch pad while laying on my back. Sometimes I have found myself wishing I had a 25 inch for this reason, however most of my sleeping is done on my side, so this doesn’t always affect me. This is something that you should think about when deciding on a pad. Also, some pads are simply rectangular in shape. My Exped Synmat that I recently purchased is this shape, and just from the little extra room at the foot of the pad makes a world of difference to me. I feel like I have tons more room than with the narrower mummy cut pads. Don’t be afraid top throw one down in the floor at the outfitter and lay around.
As for comfort, it may have been covered already, but thicknesses are the big thing to look at when comfort is in mind. Some pads are less than an inch thick, while others are around 3 inches thick. Again, you never know how they do until you lay on them. I noticed that with my Synmat, when I move around and sit up I am much more likely to bottom out than I am with my 1.5 inch Lite-Core or ProLite. I am not really sure why, but it’s the way it is.
Also, what’s inside the pads can affect comfort as well. Inside my 1.5 inch Lite-Core and ProLite, it is actually a layer of foam, whereas inside my Synmat, there is some synthetic insulation, but a large part is air. Imagine laying on a air mattress pool toy and you can get the idea (however, there is slightly more comfort to these). While my nearly 3 inch Synmat is ideally, and realistically more comfortable, I have found myself at times wanting my other pads. The Lite-Core and the ProLite has a very nice mixture of air and foam that provides a surprisingly amount of comfort that should not be looked over (in my opinion). The 2 pads just sleep different, and that’s it. The same goes for the CCF pads. The blue ones from Wal-Mart are horribly uncomfortable, while the Z Lite is actually quite comfortable.
Pads can vary as much as sleeping bags. And on that note some sleeping bags are even made to fit certain sleeping pads (check out the Big Agnes sleeping bags). The best thing is to check them out for yourself. If you can rent from somewhere, do it. If you can borrow, do it.
Be sure to check out my reviews on my individual pads by highlighting the gear tab above, then The Big 3, err… 4, and then sleeping pads. From there choose each pad.