A version of this story appeared in the 2020 summer edition of Uncommon Path.
The sleeping bag
Many bags that you can find at REI have two temperature levels: one for comfort and one for a lower limit. The label looks like this.
Comfort rating (T-comfort): If the ambient air temperature outside is this number or higher, a cold sleeper should be comfortable (provided you have paired your bag with the correct pad; see right).
Lower limit (T limit): If it is colder than this lower temperature, even a warm sleep can be cooled.
The sleeping pad
When you crawl into your sleeping bag, squeeze the insulation together. This, combined with the cold floor, is a recipe for a trembling night. So, yes, your pad cushions you against stones and roots, but its most important task is to help you store your body heat, which is measured by its R value.
R value: This value measures the thermal resistance of your pad or its ability to prevent heat loss. Most camping mats live somewhere between 2 and 6, with the higher numbers being more isolating.
The sleep system
Your bag and pad form your sleeping system. Seems to be easy, but none actually works as advertised unless it's paired correctly. Our sleeping bags are all tested on a surface that corresponds approximately to an R value of 5.4. A sleeping pad with an R-value of 5.4 is very warm and often reserved for winter camping. You're probably not using a pad as warm for three-season camping – which means your bag's temperature readings aren't accurate. Use this table to choose the right bag and pad for you.
REI co-op member Bilen Beck (bottom left) sleeps cold, so she would love the electric blanket-like warmth of this sleep system: her stacked cushions give her an R-value of 6.2, which means that she will feel comfortable Comfort rating of your pad.
REI co-op member Samuel McDonald (bottom right) sleeps warm. The 4.2 R value of his pad should make his quilt just over 30 ° F comfortable. But if it gets too hot, it can always stick out a leg or fold the blanket like a duvet.
Blen's sleep system
- NEMO Disco 15: Comfort rating 17°, lower limit 5 °
- Therm-a-Rest RidgeRest SOLite: R value 2.1
- Sea to Summit Comfort Plus SI: R value 4.1
Pad R values are additive: if you run cold, you should apply two coats for extra warmth. The inflatable Sea to Summit Comfort Plus SI is 4.1. The closed cell foam Therm-a-Rest RidgeRest SOLite is 2.1. Boom. Now Bilen is winterproof 6.2.
If you're not trying to protect your inflatable boat from punctures, put the foam pad closer to your body for a more comfortable night. Foam warms up with your body heat faster than 3 inches of air.
Sam's sleep system
- REI Co-op Magma Trail Quilt 30: Temperature rating 30°
- Therm-a-Rest NeoAir XLite: R value 4.2
Quilts are ideal for summer camping and people who run hot. However, since they lack bottom parts and hoods, they cannot be tested like other sleeping bags. If a bag does not advertise the test ratings, a is displayed "Temperature rating,” This is the honest assessment of the brand after many (non-standardized) tests.
Further equipment recommendations can be found under Uncommon Path.
Material Science: Everything you need to know about sleep systems first appeared in the REI Co-op Journal.