Choosing: Sleeping bags

Sleeping bags vary enormously in price (ours range from £29.95 to £319.95) - so what are you getting for your money? The major difference is in the type and quality of the materials, and construction. This in turn dictates the warmth-to-weight ratio of the bag and it's long term durability and performance.

Warmth verses bulk
For those who plan to carry a sleeping bag, the main factor influencing it's choice is how warm the bag needs to be verses how heavy and bulky it will be. The problem is that the warmer a bag is, the more insulation material it contains, and hence the heavier and bulkier the bag will be.

Temperature ratings
Sleeping bags are given a 'comfort temperature rating' by their manufacturer - this being the lowest temperature at which the average person will still be able to have a good night's sleep whilst using the bag. This gives a good indication of performance, but can not be taken as absolute - the problem being that how warm a bag feels depends very largely on the person in it and factors such as their age, gender, level of health and fitness, what they are wearing, what they have eaten, and other factors like humidity, windchill, and whether a sleeping mat is used or not.

Insulation materials
Down clusters and synthetic wadding are the two main types of insulation material used to make sleeping bags. The choice of which one is best depends on many factors:

Insulation	Pros	Cons	Suggested suitability
Synthetic	Cheaper. Easier to wash. Quicker drying.	More bulky. Higher weight.	Those on a budget, those who want to wash a bag regularly, those who will be using the bag in a very damp environment (e.g. sailing, rainforest or caving), those who are allergic to down.
Down	Lighter. Less bulky. Longer service life (about twice that of a synthetic bag). Softer feel. More comfortable over a wider range of conditions.	Requires specialist cleaning. Expensive. Must be dried very carefully if saturated. Some people are allergic to down.	Those who want the very best warmth-to-weight ratio, those who need a very warm bag ( -15ºC or lower?), those who want a longer lasting bag, those who prefer the feel and comfort of down.

Despite continued advances in synthetic insulation technology, down is still by far the best choice in terms of performance, however it's initial higher cost and need for specialist cleaning puts off a lot of people.

Down is no good if it gets wet?
No! This is what many people believe, but is not really the case. If you choose to throw your down sleeping bag in a river, then yes, it will be next to useless, but so will a synthetic bag. In this case, the advantage a synthetic bag has is that it will dry out much quicker afterwards. Advances in the materials used to cover down bags mean that most will cope very happily with drips of condensation and dry much quicker. Materials like Dri-Lite or Pertex Endurance have been specifically developed to provide very weatherproof protection to down filled products.

Comparing types of down
The quality and performance of down varies hugely between what you may have in a pillow at home and that which is used in the best mountaineering sleeping bags. When comparing different models of down bag, the main way to assess the quality of the down is by looking at the down's 'fillpower'. This is a measure of how much space a set sample of down occupies in cubic inches, and hence how much insulation it will provide for it's weight - e.g. a 30g sample of down with a fillpower of 600+ will occupy a minimum of 600 cubic inches. Therefore, the higher the fillpower, the better the performance of the bag. Be aware, however, that the way in which American companies calculate fillpower differs from the European method, resulting in slightly higher figures.

Down bag construction methods
Down is a loose material and needs to be held in separate compartments to ensure that it is distributed evenly (and hence gives a uniform level of insulation) throughout the sleeping bag. There are many different construction methods used by manufactures. Methods like stitched-through construction are cheap and simple, but still allow cold spots to form. Methods like V-baffle and trapezoidal construction offer much better down distribution and resistance to down shift, but are much more time consuming (and hence costly) to manufacture.

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