When the weather starts to get cold, sleeping outside can start to feel less comfortable. In our last article about shelter options, we talked about options for where to sleep. In this article, we'll talk about what to sleep gear to add to your three day pack so that you can remain comfortable, effective, and mobile.
What to Consider when Selecting Sleeping Equipment
Weight and Volume
Sleeping gear, like shelter, can consume the majority of your pack space and weight if allowed to do so. Most inexpensive zero degree bags will be up to 20L in volume and can exceed 3kg in weight. Many people won’t compromise on sleeping equipment comfort, but combine that with a desire to save money by buying an inexpensive system and the weight and volume requirements skyrocket. An example below shows the authors standard sleep kit (Level 7 ECWCS layers, a Kifaru Woobie, and a USMC Bivy) and their size comparison to a 35L (2185ci) Mystery Ranch 3DAP. When loaded, there is no room in the 3DAP for mission gear. Compare that to the same gear loaded into the 61L (3755ci) Mystery Ranch SATL, leaving about 25L for mission gear.
Whatever the weather report says, assume it will be 5-10°C colder. Sleeping gear has to keep you relatively warm. Compromises can be made here if you’re willing to deal with some discomfort over night.
How well does your sleep system deal with water. Even drybags can leak, and a sleep system set up on the ground may receive splashes from rain or become dew-covered overnight. A down sleep system will not retain warmth if wet, and must be protected.
Can you easily set up and take down your sleep system? If suddenly called to action, how quickly can you get out of it and into the fight? How quickly can you pack it and bug out if required?
In some cases you may be able to compliment your sleep system with shelter. A bivy or tent may reduce the need to use waterproof sleep gear. The protection of shelter may also help reduce the necessary temperature rating as you’re protected from the wind. Conversely, no shelter means you need to choose some extremely good sleeping kit.
You spend all day wandering around in insulating layers. If you’re taking them off only to replace them with the warmth of a sleep system, you may be wasting the space in your pack. Remember that any insulating layers you pack can be used to supplement your sleep system. In some cases, you may be able to replace the need for a sleep system all together with your clothing choices.
To prevent heat loss through conduction, you need to place an insulating layer between you and the ground. Sleeping pad can be inflatable, closed cell foam, or a combination of the two. It’s important to consider the ‘R’ value of the pad, which will inform you how well the pad insulates. Some are larger and heavier than others, and tradeoffs are made between size, comfort, and price. Also keep in mind the terrain you'll be on. Sharp thorns, rocks, or other ground debris can puncture an inflatable pad and require a repair kit. Below is a size comparison of a military surplus closed cell roll pad, a Thermarest Z Lite pad (trimmed in width), and a Klymit Insulated Static V Lite.
Three Day Pack Sleeping Gear Options
It is impossible to list all possible sleeping bags options. A good primer on what to look for in a sleeping bag is available at Outdoorgearlab.com. Ultimately you’ll have to choose between down and synthetic insulation options. While regular down packs down very small and is very lightweight, it is susceptible to moisture. Synthetic is warm when wet but can’t hope to beat the compressibility of down. Colour choice may be important if you don’t plan on using a bivy bag or tent. Snugpak and Carinthia are two of the retailers offering a good selection of military sleep systems, but lots of military surplus options exist too. Sleeping bags can be extremely bulky and heavy, or small and lightweight, but the cost and temperature rating will vary just as drastically. Being inside a sleeping bag may limit your mobility.
The poncho liner, ranger blanket, or woobie, has always been a staple of military rucksacks. It is a simple blanket made of nylon or polyester with an insulated fill. While it is not ideal for very cold weather, it will work well in warm and cool conditions if combined with layers. They come in a variety of colours, and a number of companies make commercial versions with more insulation (such as Kifaru's Woobie and Doobie, or Helikon Tex's Swagman). They pack down reasonably small but may not be as small as the most lightweight and expensive sleeping bags. Being synthetic, they are more likely to hold heat when wet. Finally, because it is a simple blanket, it does not limit your mobility like a traditional sleeping bag.
Like a fancy poncho liner, or the love child of a poncho liner and a sleeping bag. These can be down or synthetic. Some of them are built to wrap around your sides and use straps to attach to the bottom of your sleeping pad, enabling you to stay encased in the quilt. Some may find it a bit more complicated to extract from, but the size and weight benefits are substantial. Keeping a down version dry remains critical and it would have to be paired with a tarp or bivy.
An alternative to a dedicated sleep system is simply packing additional layers of clothing. The ECWCS and PCU systems will enable static operations down to -40 degrees. The benefits of sleeping in layers is that your reaction time and capabilities are not hindered. While multiple layers can begin to dominate the volume of your pack, they are not single purpose items. Clothing layers can be added or removed at any time to increase comfort based on the mission.
To prevent heat loss through conduction, you must separate your sleep system from the ground. Again, there are too many to list, but OutdoorGearLab has a solid primer on sleeping pads. Military options exist from companies like Klymit and Thermarest. Not all pads are equal, and keeping an eye on the R-value (how much the pad insulates you from the ground) should drive your decision, in combination with your other choices.
Personal Experiences and Recommendations
ECWCS Layers, Woobie, and Sleeping Pad (SA)
I chose to use existing clothing layers that I’d already packed, and supplement them with a Kifaru Woobie. The Woobie is a poncho liner or Ranger blanket. It is small, light, and easy to deploy, and more importantly, easy to stow. It takes seconds to cram it back into your ruck and you’re ready to roll. It doesn't restrict your movements the way a sleeping bag will and won't trap you if you're bumped in your position It doesn't quite provide the same insulation that you get from a sleeping bag as it does not readily seal around your body to keep the warmth in. However, it is large enough to share with a team member which provides opportunities for more warmth. Using clothing layers means that I’m not carrying any single-use insulation in my ruck and I can save that space for mission critical gear. The Z-Lite pad comes in coyote brown, and is a good way to get you and your gear up off wet or cold earth. It doesn’t have a high R value but I find it works well in most situations. If it's particularly cold, I'll pair it with an inflatable pad from Klymit. I've successfully used the layers/woobie/pad combo in temperatures down to almost -20ºC inside a shelter away from the wind. The only caveat to all of this is my feet also get cold pretty fast, so I either add my Wild Things High Loft USMC Booties (other companies make camp booties) in safe areas, or keep over boots on over my footwear.
Layers with Light Sleeping Bag and Neo Air Pad (RS)
I like to use my additional layers when possible to beef up my insulation while resting. I do try to ensure that whatever layers I am resting in are dry however, as moisture is the number one killer of warmth. While synthetic retains heat better in moisture, down compresses better for packing. My go to bag is a small down bag rated to around +5 Celsius that packs down smaller than a Nalgene. When combined with dry layers and a bivy I’ve had comfortable sleeps subzero. For additional warmth, my sleeping pad has a layer of Mylar in it that reflects body heat back. I usually like to keep my mat inside my bivy to minimize heat loss. As a final tip, I find placing an air activated hand warmer inside my sleeping bag while it’s packed in my pack makes it much nicer to crawl into and saves wasting body heat to warm up the bag.
High Loft Clothing, Bivy Bag, and Closed Cell Pad (AS)
[I] avoid down if possible. I regret having my cold weather rated bags being down bags. They lose insulating value when wet. Most quality, modern winter rated sleeping bags will be synthetic. Carefully study the specifications as the stated rating could be the comfort rating or the survival rating.
In the late fall, I would not bring a sleeping bag and generally can get by with high loft clothes, a bivy bag (as applicable) and closed cell sleeping pad.
In the middle of winter, I would probably bring a bivy bag, sleeping bag, insulated pad and insulated clothing as a sleep solution. (sometimes two pads or add debris to improve r-rating of pad). Improve or make shelter as needed. Double up on socks when sleeping and put your shoes in your bivy back to keep them from freezing if possible.
I would not use a sleeping bag without a bivy bag. I typically would favour a durable bivvy bag over the higher priced commercial ones that may not be as durable when used with debris shelters.
I am undecided if wearing my cold weather insulating clothes while in my sleeping bag adds to or compresses the loft. YMMV.
Bivy, Down Quilt, Sleeping Pad, and Layers (JL)
GoreTex bivy bag: add some weather resistance from the insulating layers and abrasion resistance for your pad (pad goes inside the bivy bag)
Down quilt: very warm, lightweight, and packable insulating layer, but cannot get wet (hence the bivy bag + tarp). Choose the appropriate weight that works with additional layering of clothing or sleep system (adding fleece liners, nesting inside a summer or 3-season bag for winter camping if necessary). Quilts vs sleeping bag: the underlayer of sleeping bags does not provide much insulation during sleep and adds weight and packing size. Down vs synthetic: down offers much higher insulation properties for its weight and is also more packable than synthetic insulation. The quilt gets double bagged in it's own stuff sack (which is DWR coated) and then into a silnylon dry bag. I also use a rain cover on my ruck to stop water from seeping through the fabric or zippers.
For warmer temps, the MEC Talon Quilt is quite good for what I got it for although it's not warm enough for freezing temps on its own (it has a limit temp of 0C). For anything colder, layering with a bag or liner is a good idea. I did get it on sale when it was first introduced so the value isn't as good now. If you have the money, Little Shop of Hammocks is a Canadian manufacturer of custom quilts and are excellent quality. A production American counterpart to LSoH would be Enlightened Equipment, which geartrade.ca stocks. Bear in mind down quilts are quite expensive option marketed specifically to the ultralight community. They are far lighter and pack up way smaller than a comparable synthetic sleeping bag though.
Thermarest XTherm inflatable pad: Very small and lightweight pad, highest R rating in a sleeping pad which is just as important as bag or quilt's temperature ratings for keeping warm. Primary concern with the XTherm is crinkling noise and cost (but it's worth it for the additional warmth especially late fall, winter, and early spring use). Could be substituted with a closed cell foam pad during warmer nights.
Small camp pillow: could be inflatable or stuffed. Could be substituted with a dry bag filled with clothing layers.
Clothing layers: keep insulating layers on as required for low temperatures during nighttime and to maintain operational readiness. Having a quick lace system on your boots or side-zip boots lets you take them off to sleep but very quickly put them on.
Bivy, Inflatable Mattress, Woobie, Sleeping Bag (STPW)
US bivy, Kymit inflatable mattress, woobie, Snugpak Sleeper Lite. Does me well for late October early November and even March in Oklahoma. For shelter either the Snugpak Stasha or a plash if you want a heavier insulating layer does great.