When looking to purchase a sleeping bag there are many things to consider, the three greatest issues are shape, fibre and temperature. For most adults purchasing a single sleeping bag the main choice of shape is either rectangular or mummy, with two different fibre options of down and synthetic and the temperature rating of the bag for the time of year and environment the sleeping bag is to be used in.
Rectangular Sleeping Bags:-
Available in various sizes to suit most body shapes, this style of sleeping bag has a square bottom with the same width top and bottom allowing the most comfort. The more technical come with a hood and mostly the comfort and patterned bags come without. Often two of the same rectangular sleeping bags can be zipped together to offer one oversized double.
Mummy Sleeping Bags:-
Often referred to as tapered or mummy sleeping bags, these are more tailored in shape to offer a smaller pack size and a greater temperature rating due to less empty bag to heat. Most mummy sleeping bags come with a fixed hood or cowl to add comfort and reduce heat loss.
Sleeping Bag Fibres:-
Sleeping bags can be filled with 2 different types of fillings - either down or a synthetic fibre. Down (as it suggests) is the same as found in household pillows and duvets, either goose, duck or eider; if you suffer from allergies this is not the bag for you. Down bags have the benefit of being able to pack away very small as the feathers allow for a greater compression and also become very light, so if you are looking for a compact or lightweight sleeping bag these are great. The drawback to a down sleeping bag is if packed away wet it can become compressed into a solid lump and once it loses its springiness it is impossible to get it back. Price also plays a big part as a down bag will always be a higher price bag to a synthetic fibre model.
Mainly due to the price of most down sleeping bags, synthetic fibre sleeping bags are the most popular. The construction of the fibre consists of polyester filaments arranged to perform the same as a down bag would, air is trapped around the fibres allowing you to keep warm. The other major benefit of a synthetic bag is its resistance to damp - if this bag gets wet it will still keep performing while damp at a reduced rate but can then be dried and it will perform again as before, most synthetic sleeping bags are also machine washable. Due to the advancement of fibres compact sleeping bags and lightweight sleeping bags now come also with a synthetic fibre fill.
Sleeping Bag Temperature Ratings:-
All sleeping bags are measured in a season rating system that is independently given by a testing station, informing the consumer of the bags performance
One season - suitable for summer use, light weather use, ideally for a climate no harsher than the UK in the height of summer.
Two season - like the one season but these bags will have a higher temperature rating, allowing the bag to be used in a normal spring and autumn.
Three season - these bags will keep you comfortable on most occasions excluding a hard winter.
Four season - a sleeping bag suitable for all year round use.
Five season - intended for expedition use or at altitude in snow conditions.
Over the last few years a newer classification system has been introduced, consisting of a European standard that gives rating in three temperature ratings. (Not all manufactures are using this system at present)
Comfort - The lowest temperature at which a normal person in a normal sleeping position will be comfortable and not cold using this sleeping bag.
Limit - The lowest temperature at which a normal person in a rolled up body position will be comfortable and not cold using this sleeping bag.
Extreme - the lowest extreme temperature at which there is a risk of hypothermia.
Other factors do play a part in this system as everyone’s body will perform differently; these include sex - male or female, your age, weight and health, clothing and whether you’ve eaten recently. These tests all are classed as a normal person which in part is of the standard woman.
For most people a one - two season bag is all that is needed for fair weather camping, we also enquire to people's sleeping arrangements - for instance if you move a lot in your sleep, or spread out then a rectangular sleeping bag is normally the best allowing you the extra room for movement. If you like to feel enclosed and secure then the mummy sleeping bag is the one for you.
Sleeping bags will either come in a stuff sac or compression sac for storage and transportation. To save having to pack your bag in the same rolled and neat fashion in which it will arrive from the manufacture, the stuff sac allows you to stuff the sleeping bag back into the bag quickly and easily. A compression sac is the same style of bag but has additional straps at the side to compress the bag further, making a smaller and tighter pack size. When not in use we would always recommend slackening off the straps so as not to over stress the bags fibres.