The sleeping bag display at the local outdoors store is overwhelming. They hang on display and the options are endless. Temperature ratings start at subzero. The weights range from ultra light to anvil-esque. Then you have to consider compressibility, whether it has good airflow, consider whether you want mummy-style or the standard rectangle, decide if you are concerned about moisture. And of course, the costs range from below $100 to over $500.
One of the most important factors in determining what type of sleeping bag to get is the temperature rating. In the United States, standards of temperature ratings vary by manufacturer. Without standardization the sleeping bag you purchase for 20-degree comfort may leave you cold at 25 degrees. Fortunately, standards exist in Europe that are more accurate in determining the comfort factors of a sleeping bag. Unfortunately few U.S. manufacturers have started using the standards.
A sleeping bag is basically an insulated filling encased in some type of protective material. Sleeping bag insulation is either synthetic or down. Synthetics are typically less expensive than down, but both have advantages and disadvantages. Synthetics have come a long way from the old polyester-filled bags; new synthetics are warmer, lighter and longer lasting than ever before. Synthetics will also provide insulation even when they are wet, so if you backpack in a damp climate the synthetic fill should be your choice. Down, on the other hand, is lighter and usually warmer. The down side to synthetic filling is the added expense and the poor insulation quality when it is wet.
Moisture is the devil when it comes to comfort in a sleeping bag. The human body generates a lot of moisture when it is sleeping, in other words you sweat a lot while you snooze. The ease with which your sleeping bag allows sweat to evaporate is important. Remember, down filling isn't good when wet, so smart manufacturers encase the down in a waterproof lining. Waterproof can sometimes mean unbreathable (allowing moisture to evaporate) and in terms of moisture retention, breathability is important. Newer materials are available now that are waterproof and breathable.
Mummy-style sleeping bags are preferred for backpacking. They are smaller, lighter and usually warmer than rectangle sleeping bags. These bags have a hood that can cinch down to a small hole to allow the occupant to breathe while keeping the heat in and the cold air out. Rectangle sleeping bags are best for slumber parties and car camping. Avoid them for backpacking.
Remember that in backpacking, one of your major tools is your back. When your back is tired and sore from carrying too much weight, it can make for a long day. A sleeping bag can be a heavy accessory. In choosing a sleeping bag, synthetics are usually heavier than down, but it all comes down to how much you are willing to spend and how strong your back is.
