Cold Feet? Consider a Vapor Barrier

Cold feet while sleeping? Consider your options. Recently I was out backpacking and I underestimated how low the temperature was going to drop. It had been unusually warm the week before and I let that influence my choices in the gear I took on my trip. When the temperature dropped during the night I used everything I had to supplement my sleep system but my feet were still cold. I discovered a trick that I’ll share that you may just come in handy one day.

It’s no surprise that when the temperature is low if you don’t do something extra for your feet they’re likely to get cold. Think about it, your feet are the farthest away from your core when you’re laying flat. Because I sleep in a hammock most nights when I’m outdoors, my feet aren’t just far away but are also slightly elevated as well. Being far away and elevated means less blood flow to your extremities which means less warmth. From my experience taking a few extra steps for your feet can make the difference in a good nights sleep during cold weather.

So here’s the scenario, it’s cold out. The exact temperature doesn’t matter, let’s just say it’s cold enough outside that you’re within 10 degrees of your sleep systems forecasted limits. So if you’ve got a 40 degree setup let’s say it’s in the 50s. If you’ve got a 20 degree setup it’s in the 30’s. In those ranges your system may be adequate to keep your core warm, especially if you’re supplementing extra layers or even a jacket. I do it all the time, give my sleep system a boost by wearing a down puffy jacket. It can make a big difference in keeping your core temperature warm, the problem is your feet.

The problem stems from how most sleeping bags and quilts are designed. The majority of them are uniform in their thickness meaning if you lay your bag on the ground and measure how much loft you have it’s going to be about the same at the top, middle, and bottom of your bag. That’s pretty common with most bags and quilts. I have seen some of the newer bags and quilts on the market advertising extra insulation in the footbox. Cottage vendors in particular will gladly accomodate your requests and beef up the footbox if you ask them to for a reasonable fee when you order from them.

For most people though you probably have a bag or quilt that has a footbox rated at the same temp as the rest of the system. When you put on that down puffy or some type of extra layer for your core, your feet are still fighting to keep warm and could also use an extra layer of some type to help.Typically if I have any extra insulation, I’ll stuff it in the footbox of my quilt to give my feet that little extra boost. A sit pad underneath your heels. An extra jacket, shirt, or any clothing not being worn wrapped around your feet. You’ve only brought the stuff on your back, and that’s what you’ve got to work with and you need to make it all work for you.

In the case of this particular night I was wearing every bit of clothing I had. My tarp was hung low to cut down on the wind, which was blowing strong. My core was okay, and for the most part I wasn’t cold but my feet were. I put my backpack in the hammock under my feet to help insulate them, but it wasn’t enough. I only had one piece of gear left that wasn’t being used, my pack liner which was a trash compactor bag. I decided to put my feet in the compactor bag and then put that in the bottom of my quilt. I had little faith it was going to make much of a difference, but 15min later my feet weren’t cold anymore. Shazam!

We’ve all read and heard about the problems of condensation in your sleep system. Even with it being cold out, I was thinking about condensation and wondering if I was going to regret using the compactor bag. I was wearing two pair of socks, my third pair was on my hands as mittens. 🙂 Not knowing what to expect, I took off one pair to keep in reserve in case I ended up with a rainforest around my feet. Luckily nothing of the sort happened. My feet stayed warm the whole night, I woke up with a slight layer of condensation in the compactor bag, and a big smile on my face knowing I had learned a valuable lesson.

The lesson I learned is that a vapor barrier, in this case the trash compactor bag around my feet, can add a significant amount of warmth in a pinch. I’ve used this same trick numerous times since to confirm it’s effectiveness. The warmer it is outside, the more condensation you can expect in the compactor bag. Normally when I get up I take the compactor bag out and hang it inside/out and it dries quickly. Hopefully, if you find yourself insufficiently insulated this trick might help you out.