Guide to Sleeping Bags
Sleeping Bag Guide
Most of our trips, treks and expeditions will require you to have a sleeping bag. Choosing the right sleeping bag can be a bit daunting when faced with the huge array of brands, models, fillings, ratings, colours etc. The following outline information is intended to help you to make a decision on which sleeping bag to buy or hire.
At the bottom of this page are recommendations for specific trips.
Sleeping bags are mainly there to keep you warm and therefore allow you a good night's sleep. It does this by insulating you against the air around you, but not really from the ground (more on this later)
There are two main types of insulation that the sleeping bag may use; Synthetic and Down.
Synthetic insulation is usually heavier, bulkier, more robust and cheaper but will keep you fairly warm if it gets wet and will also dry out in a reasonable time. There is a range of different types of synthetic insulation, getting more expensive as they get more high-tech and thus providing more warmth for less weight and bulk. They are evolving and improving all the time. Products like Primaloft, Thermolite, Climashield and Quallofil are examples of high-end synthetic insulation.
Down insulation (the small fluffy feathers from birds) is lighter, packs down smaller, more expensive but if it gets wet it won't keep you as warm.
The decision on which filling is right for you will, therefore, be decided by things like:-
- Will you have to carry it long distances on your back? Yes - Consider a Down bag
- Is it likely to get wet and then not be able to dry it? Yes - Consider a Synthetic bag
- Are you likely to be sleeping in temperatures of -5 degC or less? Yes - Down bags may be your only option
- Are you very short of money or possibly won't use it again? Yes - Consider a synthetic bag
More on Down Insulation
Down insulation is also available in different qualities, this depends on which bird it came from and what proportion of it is down vs feathers. Eider duck down is usually the best, goose down the next best and duck down slightly less so. The proportion of down to feather may be specified as a percentage. For example, 90/10 would be 90% down, the higher the first number the better. The down is also often given a 'Fill Power' rating. This is a measure of how much the down puffs up and traps the air that will insulate you. If it puffs up more, you need less of it to do the same job. Again, the higher the number the better, numbers of 750 or higher are good. Just to confuse things, tests results to the US system will come out higher than the European system. See this video of a US fill power test.
You should also check whether the down is responsibly sourced. Down clearly comes from birds and therefore the way in which the birds are reared and how the down is collected is of relevance. At one extreme, geese may have the down feathers plucked from their breast region whilst they are still alive. Some down, such is sourced from birds slaughtered for their meat and is gathered from the dead bird during processing. At the other extreme, some manufacturers such as Tundra claim to only use down that has already been naturally moulted by geese that are reared for breeding purposes. There is an organisation called the European Down and Feather Association who have a code of practice related to this, members are required to conform to this standard. The outdoor company Patagonia have also now produced a standard that they have committed to follow on the ethical sourcing of down for their clothing. We all have a duty to question manufacturers so that they are put under pressure to ensure that down is responsibly sourced.
Different people will feel warmer or colder in exactly the same sleeping bag in exactly the same conditions. Generally, there are quite large differences between men and women, with women usually requiring a bag rated 5-10 degrees warmer. Therefore there is no one perfect measure that will tell you if a sleeping bag is right for you.
However, there is a measurement system that you can use to help guide you. Not all manufacturers will use this system but if the sleeping bag has EN13537 written on it next to the rating, then they are. Explanatory video on youtube. The rating system does not give one number for the bag, it gives a few. These are summarised as follows:-
Upper Limit = The highest temperature at which a standard man would be able to sleep in the bag with the zip open and their arms and head out. Hotter than this and they will be sweating and unable to sleep.
Comfort Temperature = The temperature at which a standard woman would sleep comfortably in a normal relaxed position.
Lower Limit = The temperature at which a standard man would still be able to sleep for 8 hrs without waking up due to the cold, though wearing baselayers and hat and curled up.
Extreme = The minimum temperature at which a standard woman would survive for 6 hrs without hypothermia.
The standard man is modelled as the average 25-year-old weighing 73kg
The standard woman is modelled as the average 25-year-old weighing 60kg
In conclusion, the most useful temperature rating to use would probably be the 'Comfort Temperature'. If you read what the sleeping bag is rated as and then make a decision based on your how much you feel the cold.
For example, if a sleeping bag was rated with a comfort temperature of +8 deg C and you were expecting to use it in temperatures of down to +5 deg C; if you are a woman who feels the cold you may not get any sleep but if you were a man who usually gets too hot at night you might be OK. Also, bear in mind that it is generally much easier to cool yourself down than heat yourself up at night. Therefore you may want to go for a warmer sleeping bag and just unzip it to your waist if required.
Example of a sleeping bag rating tag
Note that it is the "Comfort" temperature that is most useful, in this particular case it is +8 deg C. A lot of people would be uncomfortable sleeping at +3 deg C in this, bag and some would be on the verge of hypothermia at -11 deg C.
As mentioned above, a sleeping bag only really insulates you from the air around you, not from the ground beneath you. This effect can be enormous and even the best sleeping bag is likely to be useless without an appropriate mat, especially if you are camping on rock, snow or ice. You must have an appropriate mat in conjunction with your sleeping bag.
There are two main types of sleeping mat; Closed Cell Foam and Inflated/Self-Inflating.
Closed-Cell Foam Mats are the traditional old-school camping mats. These are very light but quite bulky and limited in their insulating properties. Their huge advantage is that they are robust and will still work if they are punctured by a knife, thorn, crampon etc. they can also be used immediately with no need to inflate them.
Inflated Mats will generally pack much smaller but may be slightly heavier. They can, however, be made much thicker and can, therefore, be much more comfortable and much more insulating, especially if they contain down insulation as well as air. The big potential disadvantage with these mats is that they are useless if they are punctured. It is therefore essential that you carry a repair kit for them. Also, bear in mind that blowing them up with your mouth will put some moisture inside them. This is not generally a problem, but if you are in a cold location this may turn to ice and build up inside. It will also start to affect the performance of any down filler inside.
On high altitude mountain climbs, we will normally carry both a closed-cell mat and an inflating mat.
Other Things to Bear in Mind
You usually pay more for a lighter sleeping bag of equivalent warmth. This may be due to more high-tech materials but also smarter design. However, some products right at the lightest end of the scale may not be as robust and may not last as long. They may also need a bit more care when in use.
Not all sleeping bags are the same length and width. If you are tall, wide, have an aversion to tight spaces or have a particular way of sleeping; you may want to check the dimensions of the sleeping bag and maybe even ask to open one out in the shop and snuggle down inside it!
There are a few different shapes of sleeping bag available.
The simple rectangular ones are cheap for a reason! They are not really useful for anything beyond a sleepover in the lounge or in a caravan.
A 'mummy' shaped bag is the norm as it works more efficiently in that it traps air for insulation purposes within the wall of the bag but does not have excessive pockets of air between you and the inner wall of the bag. These pockets of air can make it take longer to get warm and cool down more easily. Mummy shaped bags also make more efficient use of material and are therefore lighter and less bulky for the same overall size. Some people find the narrower or more shaped fit a bit constrictive, particularly if you happen to have wide shoulders or a particular body shape. As with our advice on size, it can be well worth asking to get inside the bag to try it out, even if you feel a bit silly lying out on the shop floor!
There are also some new 'pod' shaped sleeping bags that are much wider and allow you to curl up inside them and sleep in a variety of shapes. This may work well for general comfort but does make for a much bulkier bag and so is not likely to be particularly well suited to travel where weight and bulk of the packed bag is a factor.
Particularly at the cold weather = warm sleeping bag end of the spectrum, the design of the sleeping bag can vary quite a bit. Some models will have certain features to try and improve performance. These might include the shape, size and layout of the pockets in which the insulation is distributed, particularly with regard to avoiding cold spots where insulation may not be well distributed. A well-shaped hood that can close down around your face and keep you comfy is very important in cold conditions. Another feature that can be very useful is a baffle that can be independently closed up around your neck to fit the bag to your body shape and avoid any draughts.
As with a lot of cheaper clothing, cheaper sleeping bags may have lower quality zips and zip detailing. The last thing you want is not to be able to close your bag if the zip is broken or swallows up a wad of fabric and jams. Good bags will also have a baffle on the inside of the zip so that you don't get a strip of cold along with it.
You can use silk, cotton or fleece sleeping bag liners to help keep the bag clean and also get a few degrees more of warmth.
Looking After Your Sleeping Bag
As with all kit, it will continue to perform well for longer if you look after it. When not in use it is best stored laid out flat in a dry place. It should not be left in its stuff sack and ideally not hung up. Some sleeping bags come with a small stuff sack for using on a trip and also a much larger cotton bag for storage at home.
Washing your sleeping bag is possible, see video from Trail Magazine, but will inevitably reduce its performance of done too often. If you use a liner then this can help reduce the need for washing. If you do need to wash it then you need to do it carefully by hand using special washing liquid that won't leave a residue. You can then tumble dry it on a low heat setting, although your machine is unlikely to be big enough for a 4 or 5 season bag. Adding a tennis ball to the drier can help to break up and 'clumps' and help to re-loft down.
When carrying/using your sleeping bag you should try to keep it dry at all costs. Carry it in a waterproof stuff sack. In addition to rain, snow and rivers, the bag can get damp from steam from a stove or drips/ice crystals falling off the inside of a tent. If it gets damp then air it at the first opportunity. Using a gore-tex outer bag can be useful in certain environments and some bags come with a water-resistant outer shell material. Beware though, some of these outer shells can also be quite air-tight. Therefore if the bag is fully puffed-up and you jump on it you can damage the stitching or even pop it like a balloon!
When you get your sleeping bag out of its stuff sack it will need some time to 'loft' or 'puff-up' before it is at its best. Therefore it is wise to lay out your sleeping bag at least an hour or so before you get into it.
Where to look for Sleeping Bags
In addition to your local outdoor shop, you can look at outdoor magazines for gear tests. Ther are also online sites that will compare various products against certain criteria.
Websites like sleepingbagshop.co.uk or alpkit.com are good for ideas, although they don't carry all brands. There is quite a good tool on the PHDesigns website but bear in mind that their kit is top of the range, low volume and therefore expensive.
Suggested Sleeping Bags for Particular Trips
Please note that this is just a rough guide, as mentioned above, warmth can be very subjective. If you feel the cold then do go for a bag that is warmer (rated to a lower comfort temperature) or take some thermals or a silk/fleece/cotton liner as well. Do speak to us if you have any doubts or questions before spending your hard-earned cash on a new sleeping bag.
|Trip||Insulation Type*||Comfort Temperature**|
|Borneo trips||Synthetic or just Silk liner||10 deg C|
Kenya school & university trips
|Synthetic or Down||0 deg C|
|Mount Kenya||Synthetic or Down||-5 to -10 deg C|
|Nepal treks||Synthetic or Down||-5 deg C|
|Mount Kinabalu||Synthetic or Down||0 deg C|
|Mount Toubkal summer||Synthetic or Down||-5 deg C|
|Mount Toubkal winter||Synthetic or Down||-5 deg C|
|Mount Kilimanjaro (tents)||Synthetic or Down||-10 deg C|
|Ojos del Salado (Tents/Huts)||Down||-10 deg C|
|Elbrus South Route (Huts)||Synthetic or Down||-10 deg C|
|Elbrus North Route (Tents)||Down||-20 deg C|
|Island Peak (Tents/Lodges)||Synthetic or Down||-15 deg C|
|Mera Peak (Tents/Lodges)||Down||-15 deg C|
|Aconcagua (Tents)||Down||-20 deg C|
|Khuiten Peak (Tents)||Down||-20 deg C|
|Muztagh Ata (Tents)||Down||-30 deg C|
|Mount Everest (Tents)||Down||-40 deg C or lower|
* This assumes general material specifications. High-grade synthetics can out-perform low grade down and may be more appropriate in case of extreme allergies or locations where there may be significant moisture or potential condensation and ice buildup.
** This is only a guide and assumes that the sleeping bag has been graded according to EN13537. Also, ensure that you read the right part of the sleeping bag rating tag or description, some marketing literature can be misleading and quote the Lower Comfort Limit, what is given here is the Comfort Temperature, see section above on ratings for an explanation.