I tried to test my sleeping set up tonight. Second screenshot has weather in metric for the night.
Had warm baselayer on, sleeping bag rated for -8C plus reactor extreme bag liner and had an alp mountaineering sleeping pad that says it is rated 8.1.
I was cold from below from the start, but definitely warm on the top. The cold was from most protruding parts of me on the bottom. Hips and shoulder when on the side, butt and upper back when on the back.
After hour or two of sleeping I woke up and went indoors for the rest of the night.
Is this reasonable experience with the gear and weather? Or the sleeping pad overestimated its raiting by a lot
by Nesseressi
8 Comments
I’ve slept on snow with a pad with an R rating of 6.5, at -17C without issues. Based on what you tell, I’d definitely suspect that rating of 8.1, too.
I guess you could inflate it more, but airpads are comfy partially because you don’t have to fill them too hard.
Standard bag ratings are for survival tempers. So, the real rating for comfort on that is probably more like -3C. And the pad is probably over rated as well.
If you could tell it was coming from the ground, then it was probably from the sleep pad. I find it helpful to use a 3 season pad on top of a closed cell foam with a reflective side to keep me cozy. Also good to note that -8 could be the survival rating for your bag, not the comfort rating. I find a lot of the time I’m comfortable about 10C warmer than my bag is rated for.
Also keep in mind what you did before bed- I always make sure I have lots to eat, some kind of warm hot chocolate or some sugar right before bed, and I’ll throw a sealed nalgene full of hot water in the bottom of my sleeping bag to get it warm before I climb in- its always easier to stay warm then to warm up. If you’re low on calories and your gear is ice cold, you have to work a lot harder to get/stay comfy
You 100% want a bivy!! And winter rated air mattress with highest possible R Value for your Warmest dryest option! Oh an a sleeping bag rated for -20.
What was the bag fill? Poly or down? It could be compressed so you don’t have much insulation over the pad. I agree with other comments to put foam below the mattress for extra insulation and also that the bag isn’t really rated for being comfortable at this temperature. Also the reactors sleeping bag liners don’t seem to work well from my experience.
I like this part:
“After hour or two of sleeping I woke up and went indoors for the rest of the night.”
You have to not get in contact with the cold ground somehow. Cot or something else to get you off the cold ground.
If you were warm up top and cold against the ground, then it’s a failure of the pad. You did yourself a good thing by testing in the back yard. I’ve seen lots of folks take gear out of store packaging while setting up on site.
I always double up ground insulation in really cold weather. If I’m car camping, I throw down a layer of rigid foam insulation I got from the hardware store. I custom cut it into pieces that fit the inside of the tent. If I’m backpacking then I add a foam pad under my sleep pad. There have been several videos in recent years talking about how much better foam sleep pads are at insulating.
Yeah, that experience makes total sense, and your gear probably isn’t “broken.”
What you’re describing is classic heat loss from below. Your sleeping bag and liner are doing their job on top, but once you lie on insulation, it gets compressed and basically stops insulating. At that point, your sleeping pad is doing almost all the work. When it’s cold, any weak spot shows up fast—especially hips and shoulders for side sleepers.
A couple things likely stacked against you here:
* Snow + frozen ground is a massive heat sink. It pulls heat out of you way faster than bare dirt.
* Side sleeping concentrates pressure on hips and shoulders, which reduces effective insulation even with a high R-value pad.
* Pad R-values are lab-tested in ideal conditions. Real-world factors like movement, snow, wind, and body shape can make them feel lower.
An R-value around 8 is solid, but at temps where it feels like -9°C, many people still need either a foam pad underneath (cheap and very effective) or a slightly warmer setup than the numbers suggest. A thin closed-cell foam pad under your inflatable often fixes exactly what you’re describing.
So yeah—this sounds like a realistic outcome for those conditions, not a wildly overestimated rating. Your top insulation worked; the ground just won the battle.