Sleeping Bags: What you should know

Facts:

There is no current "standard" for temperature rating of Sleeping Bags.
There is no Sleeping Bag that is "right" for every condition.
There is no Sleeping Bag that is right for everybody.
What keeps you warm, may not keep me warm.
Air temperature is not the only factor that effects body warmth.

What should you consider when purchasing a sleeping bag:

Your own warmth factor as related to those around you. -Do you wear a t-shirt while others are in jackets, or vice versa? Also remember that it is harder for your body to produce body heat, when you are tired and not up moving around.
What type of camping will you do, primarily? Backpacking, tent camping, or camper/cabin camping? If you will have to carry your Sleeping Bag for a ways, you will want to be sure that it is compact and light weight.
What kind of weather conditions are you apt to encounter? We are located in the North East and often have rainy, cold, damp, conditions, even in the summer. Dampness will have a great effect on the chill factor. As well as sometimes having an adverse effect on your sleeping bag's ability to keep you warm. (see Down Sleeping Bags)
Personal sleeping habits. Do you like to move around while sleeping? Some people feel too cramped in traditional mummy style sleeping bags. They need to have room to move around some.
Even though there is no "standard" for temperature rating of sleeping bags, all of the manufacturers assume two important factors. First is that the bag will be used with a ground pad or cot. Second, that the bag will be fully zipped up and, if there is a hood, it will be used.

How Sleeping Bags keep you warm:

Sleeping Bags work on the principle of capturing the heat your body produces. The thickness of the layers of the bag, is called the loft. The most important factor is creating trapped air space. It is the warmed air trapped in this air space that keeps you warm. Goose down bags are so highly rated because the down creates the most airspace with the least amount of added weight to the bag. Goose Down is also the most compressible. HOWEVER, there are some very important drawbacks to Goose Down. If Goose Down gets damp, it loses most of it's loft and is not easy to dry. Plus, Goose Down tends to shift with time and bunches in one area, leaving other areas of the bag with no fill.

It is for these reasons that other, fiber fills, have been developed. FeatherLoft™ is a good example. FeatherLoft uses single channel micro denier insulation for air capture and increased loft. Added silicon increases loft and provides water protection. Hollofil by Dupont is another fine sleeping bag fill. Since the fiberfill bags do not absorb the dampness, they can keep you warmer if you are camping in these conditions.

Although the fiberfill bags are often heavier and less compressible than the Goose Down, they are much more durable and affordable.

Types of Bags:

Mummy Bags - Mummy Sleeping Bags are broader at the shoulders and narrow at the feet area. They most always have an insulated hood that greatly enhances the bags ability to capture and hold in body heat. The advantage of this shape is that there is less area for your body to warm up and they are lighter weight and more compressible. The disadvantage is they do not allow much room to move around.
Rectangular Bags - The Rectangular Sleeping Bags allow much more room to move around and because they tend to be bulkier and heavier, are much better suited to those who do not have to carry their equipment very far. Another feature that many enjoy, is that these bags can be zipped to another bag, therefore they are popular with those that love to snuggle. A disadvantage with these bags was that there was no hood and much body heat was lost. Nebo has added the hood feature to all of their Rectangular Bags, so this no longer needs to be a factor.
Oversized or Double Bags - Fairly new to the scene, but very popular, are the Oversized and Queen Size Sleeping Bags. These are definitely not meant to be carried far. They are bulky and heavy but they offer comfort and warmth to many who find the more traditional Sleeping Bags to be too small and confining.
Modular Bags - These bags are typically the Mummy Style. But it is worth noting that these bags are like a Sleeping Bag inside another Sleeping Bag. This offers more versatility for camping in different temperatures. If summer camping, you can elect to bring only one of the bags. If you will be in colder temperatures, both the inner and outer bag will offer the added insulation needed.

Outer Shell and Lining :

Most important of these is the outer shell. The Nylon shells offer an advantage in that they do not absorb moisture, thereby adding to the warmth factor. This is not to say that they will not get wet in the rain. If you will be outdoors in wet conditions, it is recommended that you consider a bivy bag or shelter made to be water proof.

For added durability it is recommended that you consider a rip-stop outer shell. As Sleeping Bags tend to be used in rough conditions, this feature protects against snags and tears caused by hidden hazards in the outdoor environment.

The lining of sleeping bags include Rip-Stop Nylon, Nylon, Taffeta, Polyester, and Flannel. This is not a complete list but the most common materials used. The lining of your bag is not quite so important so your personal preference for comfort should be considered.

Summary:

All bags are not created equal but all brands of similar bags are not that dissimilar. This means that if you consider your usage and the conditions you will most likely be camping in, you can purchase a high quality Sleeping Bag without breaking the bank. This also allows that if you may be camping in different conditions and or seasons, you may even consider purchasing two separate bags. Again, this does not mean you have to take a second mortgage on your house.

We have done a "side by side" comparison of two sleeping bags that shows that feature for feature they are very similar. One is a well known brand and the other is lesser known (albeit they are quickly becoming recognized for their quality bags). In the example we use, the better bag is actually less expensive simply due to brand recognition.