Rectangular Sleeping Bags
Sleeping bags come in several major shapes. Each shape and style is better suited to certain uses or sleeping styles. One of the most common shapes is rectangular. This shape, the roomiest and most relaxed, is best if you turn or shift in your sleep. However, the bags' roomier interior means they are not as warm as other shapes and can be quite bulky.
Semi-Rectangular Sleeping Bags
Semi-rectangular sleeping bags taper at both ends while remaining wide at the center. This makes them best if you want a less bulky shape than standard rectangular bags and a more accommodating width for a larger waist. Examples include the Katahdin ClimaShield Sleeping Bag from L.L. Bean, and the Sandpiper from Feathered Friends.
The mummy bag is wide at the top and narrow at the bottom. This makes these sleeping bags close-fitting and one of the best for colder climates where the insulation of natural body heat is essential. Its close fit also prevents cold drafts when you shift or move in the bag. Many also include a hood at the top end to further conserve natural body heat. Examples include the Hillary Extreme Mummy Sleeping Bag from Sears, the Everest Mummy Sleeping Bag from Walmart, and the Coleman Taos 25-Degree Mummy Sleeping Bag, available at most general sporting goods stores.
The shell of a sleeping bag is the outside material. Some of the best, cheap material for budget-friendly sleeping bags is nylon or polyester. Examples include the Eddie Bauer Sleeping Bag with Comfort Shell. More expensive, specialized sleeping bags use premium shell material, such as Gore DryLoft and nylon. The shell material is not an especially important factor in selecting the best sleeping bag. However, if you are camping in a wet or humid environment, waterproof or resistant material such as Dryloft or microfiber are best. Sleeping bags that use these shell materials include the Marmot Pinnacle Dryloft and the Wild Cat Goosedown Dryloft bag.
Fill material is the material used to insulate the sleeping bag. Natural down from geese or ducks is best for those camping in dry environments. Examples include most of the bags from L.L. Bean as well as the MEC Drake, Gosling and Cygnet product lines from the Mountain Quipment Co-op company. The higher the fill power of a down bag, the better its insulating capacity. Synthetic fill sleeping bags, a good all-purpose choice, are best for wetter climates and for those who want a non-allergenic sleeping experience. Examples include many of Coleman's sleeping bags, such as the Fairmont and the Colossal, as well as most of Wenzel's bags.
Choosing the Best Sleeping Bag
The best sleeping bag depends on your sleeping style, body shape and camping environment. Most camping supply stores and sleeping bag manufacturers design and sell bags that incorporate a combination of all the aforementioned shapes and materials. For example, Coleman sells dozens of bag styles with varying features. If you are unsure, talk to a company representative. When you're shopping, choose a shape that feels the most comfortable. Then, choose your shell material. Finally, select your fill material.