Sleeping Bags 101
An excerpt from The Family Camping Guide
After a long day in the backcountry or a hike along a well known trail at Balsam Lake, few pleasures compare to crawling into a comfortable, warm, well designed sleeping bag for a good night’s sleep.
A lot of thought goes into that bag, by-the-way. Shape, fill, design, weight, materials, construction are only a few considerations that must be addressed before a sleeping bag gets to you.
Lets start with shape, as it’s the most obvious. You’ll see some are shaped just like a rectangle, while others are tapered and still others are barrel shaped. The shape is an important factor and depends on where and how you sleep.
Let’s say for the sake of argument that you’re going to spend a week in a cabin that has the luxury of beds. A rectangular shape is nice, as it offers the most room for stretching out. However, all other things being equal, the rectangular shape, with all the material in the corners, is the heaviest and bulkiest of the shapes. No big deal if you’re just tossing it in the trunk and running up to the cabin. Due to it’s simple shape, all other things being equal, it’s the least expensive shape to design and sew.
At the other end of the shape spectrum is the “mummy” bag. It offers the closest fit to the body, holds heat well, since there is no “extra” material or insulation for your body to keep warm and is the least in weight. On the other hand, it can feel confining and tends to be more pricey due to construction and sewing challenges.
The middle ground is occupied by various shapes such as “modified mummy,” “barrel bags,” and straight tapered rectangles. All of which have various advantages and disadvantages, depending on need.
At present, there are no mandatory standardized testing methods applicable to sleeping bags. However, those clever Europeans have come up with a good one called EN 13537. It is not required testing for Canada and so not all bags use it. Any generally accepted method for testing sleeping bag warmth assume you are sleeping on an insulated pad inside a tent.
In general here are some things to think about when determining what level of warmth you think you may need;
Typically, men sleep warmer than women
Kids sleep warmer than adults
Drinking more than the equivalent of a glass of wine will begin to constrict blood flow to the extremities and make you sleep colder
Humid air feels colder in the cold and hotter in the heat
Proper eating helps you sleep warmer
Illness can affect you either way
High altitude is colder
Physical fitness and general level of health are a factor, fitter is warmer.
Smokers sleep colder than non-smokers.
Air movement inside the tent pulls heat from a sleeper quicker than standing air.
A lot can be written about the fill used in any bag and a more complete discussion can be found in a related article titled, “staying warm.”
“Fill” is the material that is sewn into the bag which help insulate you from the cold. For the purposes of this discussion there are two types of fill; synthetic and down.
Synthetics offer the advantage of maintaining some warmth when damp, quicker drying, generally reduced price. However, they tend to be bulkier, heavier and will not enjoy the longevity of service that a good down fill will offer. This being said, there are some very good synthetics out there.
Down (primarily the under layer feathers of geese) for the same warmth, is lighter, compacts well for packing and with proper care will provide excellent service for twenty years or more. I personally have one down bag that I purchased in 1984 and it’s as warm and fluffy today as it was then. When damp, down does not hold heat well and takes some time to dry. In consistently wet conditions (West Coast Trail for example) down will be hard to keep dry, so synthetics may be the way to go. Down is typically costs 50% more for the same temperature rating compared to synthetics. Down continues to be the choice of almost every major expedition to just about anywhere.
There are basically four types of sleeping bag construction; sewn-through, off-set, baffled and triple layer. All have advantages and disadvantages, depending on need.
Sewn through, is the lightest and least expensive. The fill is sandwiched between two layers of material and then stitched through to created tubes of insulation. While inexpensive and light, a “cold spot” is created at the sewn through seam.
Off-set is, essentially, two sewn through panels which are off-set from each other to cover the cold spots. It’s heavier, more costly and difficult to build, but it offers increased warmth.
Baffled construction, essentially takes square tubes of material and stuffs them with fill. There are no cold spots and it’s not as complicated nor heavy as the off-set method.
Finally, triple layer construction basically takes a sewn-through design and drapes two layers around the panels, - one on the top and one on the bottom – thus minimizing, but not eliminating the cold seams.
Recently another construction has hit the market that seems to solve a few problems. It’s primarily intended for use with synthetics. Layered panel construction takes insulation battens and layers them like a loaf of sliced bread, having fallen over.
A foot box refers to the area at the bottom of the bag where the feet go. Less expensive bags just sew the top and bottom of the sleeping bag together, but a foot box is a three dimensional construction that allows greater comfort for the user. While sleeping on the back, the feet can remain pointed upwards without any pressure on them. Again, more costly, but a great improvement in comfort.
Hoods are usually, but not always, found on mummy, modified mummy and barrel bags. Usually controlled by a draw string, the hood can be pulled up and around the head to help hold in heat. Some bags have a hood that lays flat and can be pulled up, other, more serious bags have the hood built into the design and is three dimensional in nature.
Zippers exist on virtually every sleeping bag. They usually, but not always run down one side from the shoulder area to the feet. Some have “two way” zippers which allow you to open the foot area for cooling, if required. Some bag/zipper combinations allow you to open up the sleeping bag like a blanket. These full opening bags are typically rectangular bags.
Zipper baffles are tubes of insulation that run behind the zipper (inside the bag) to keep drafts from entering the bag.
Chest pockets are what you think they are. It’s sometimes nice to have a little pocket up near the chest, on the outside of the bag, to keep little objects you may need in the night. A good spot to keep puffers.
Bag liners are usually sold as accessories. They slip inside the bag to add a little warmth and possible comfort. In a warm environment, where sweating is likely, the liner can be removed and washed separately from the bag. Typically made from silk, polyester, cotton or a poly/cotton blend.
Over bags are, essentially, an insulated bag that slides over the outside of your sleeping bag to add a few degrees of warmth. Threads does not currently sell any over bags, but it may be possible to order them.
Storing Your Sleeping Bag
For long-term storage (over the winter, say) make sure your sleeping bag is absolutely dry. Hang it outside in the sun for a few hours and let the breeze blow through it. Store loosely in a large cotton bag or nylon mesh bag in a cool, dry place. For short-term storage, you can store your dry bag in the stuff sack that your sleeping bag came with. For trips, you can pack your sleeping bag in a “compression sack” which holds the sleeping bag and then with a series of straps, compresses the bag to surprisingly diminutive dimensions – helping reduce bulk in your backpack.
Washing Your Sleeping Bag
Not rocket science. Follow the recommendations of the manufacturer. Typically it looks like this; if down fill, use a specialty down soap (Nikwax and Granger’s both make a good one) and a large (triple load) commercial, front loading washing machine. Avoid the washing machines with the agitator as it’s really hard on the fabrics. Wash, rinse twice, spin dry, then into the drier on low to fluff and dry the down. Not too shabby eh?
If you have a synthetic sleeping bag clean exactly as above, but use an unscented, non fabric softening, powdered detergent – not a liquid
Don’t put your sleeping bag into a hot dryer as it may melt the nylon fabrics. Warm only
Use only specialized down soap with down sleeping bags
A sleeping bag really isn’t that comfortable when sleeping on the ground and that’s why every body uses some sort of sleeping pad. A closed cell, foam sheet about 13+mm will offer some comfort and protection. The thicker the better.
The most popular by far, is the Therm-A-Rest brand. Most of their models are self-inflating, by virtue of open-cell foam, sandwiched between two layers of air-tight material. Depending on the model, they can range from quite thick and luxurious but heavy to quite thin, super-light and somewhat comfortable. Weight versus comfort and bulk is always the compromise you need to make. For me, carrying a few extra ounces to gain a thicker, more comfortable sleeping pad is worth the effort.
Most sleeping pads will have an “upside” to them, which will have a slightly sticky feel to it. It just feels sticky, it isn’t actually sticky. This will help keep you from sliding off the pad during the night.
Not only do sleeping pads provide padded comfort, they also help insulate against cold. All pads have an R-value, which is a measure of insulation power. The higher the R-value the better. R-values for sleeping pads typically run from about 3 for a foam pad, up to 9 for a heavier, bulkier base camp model. Important to note that ALL sleeping bag ratings assume you’re sleeping on a sleeping pad, in a tent.
Pillows are a nice luxury. For years I’ve used a nylon mesh bag, stuffed with a fleece jacket and it was OK. Last year, I was lent a compressible foam pillow from Therm-a-Rest and it was great! On a long backpacking trip, I’d likely leave it at home as it’s still a little on the bulky side, but on a weekender or car camping I’m all in for taking it. I bought one.
Selecting the correct sleeping bag for your needs may require taking a few moments to climb into the sack. Remove your shoes, heavy belts and jackets and get right in there. Assume the position you prefer while sleeping and see if it works for you. If you have a spouse who tells you that you have the “jimmy legs” while sleeping, you might want a roomier bag. You get the idea.