Contrary to popular myth, sleeping naked in a sleeping bag is not warmer than wearing additional clothing. There are actually many good reasons not to sleep naked in your sleeping bag if you want to stay warm and preserve the investment you’ve made in an expensive bag.
Let’s assume the you have a sleeping bag that is properly rated for the temperatures that you’ll be using it for. The next biggest factor in whether you will be warm or not is the insulation rating of your sleeping pad. Unless, you have the right amount of insulation below you, the ground will absorb most of the radiant heat vented by your sleeping bag and you’ll feel cold at night. You can prevent this by using an insulated sleeping pad like the Big Agnes Air Core or the Exped Downmat 7. These pads contain primaloft and down, which trap the warmth you generate at night and reflect it back at you. This is necessary to compensate for the fact that you are lying on your sleeping bag, which compresses the down or synthetic fill, eliminating most of it’s loft and heat retention capabilities.
The next most important factor in staying warm at night will be a hat, even if you are sleeping in a mummy bag. It is estimated that 20-40% of the your bodyheat is lost through your neck and head, so covering them up can keep you warmer.
Now suppose you’ve taken all these steps and your are still cold. Well, now is the time to start putting on clothes. Start with long underwear, socks, and then a coat with additional insulation. All of these will descrease the amount of room in your sleeping bag taken up by air and increase your warmth level because your body has to heat less air in the sleeping bag around you. If you are still freezing, you can stuff more of your gear inside the bag with you, to further reduce the amount of air in sleeping bag.
More advanced techniques for staying warm utilize vapor barriers. These are primarily used by moutaineers or winter campers in extreme environments.
Finally, if you have invested a lot of money in a sleeping bag and you want to keep it for many years to come, it is advisable that you bring along a pair of long underwear (top and bottom) on backpacking trips, that you only use for sleeping in. These clothes will help keep the inside of your sleeping bag clean and prevent the dirt, oil, or chemicals such as DEET, that have collected on your body after several days, from ruining your bag. These clothes can be used in emergency situations when all of your others are drenched or they can help prevent bugs from biting you if you need to vent your bag in hot weather.
Tags
- sleeping naked
- sleeping bag naked
- naked sleeping
Good post. I've heard good arguments for and against sleeping naked. Personally I sleep hot, so I tend to wear fewer clothes in my bag rather than more.
My top tips for staying warm (other than the good ones you point out, such as wearing a hat and getting a good sleeping pad) include:
- eat fats before going to sleep. A handful of peanuts, salami, etc. The slow burn will keep you warm. Garlic tablets (or anything of that family, such as pickled onions) also promote blood circulation.
- fill your water bottle with hot water, and take it in with you. For extra heat, put it between your thighs where it will heat the blood that passes through the femoral vein.
- do a few situps or leg-pumps when you first get in (but not so many that you start to sweat!). This gets the blood flowing, warms the muscles and also pumps warm air into the insulation of the bag.
- place unused clothing (jacket, etc) under your mat.
as an old 11B with more than a few nights spent sleeping outside, i'd suggest that you always orient your sleeping arrangements so that your feet are on the downhill side of your body.
that way, they get full blood flow, and stay warmer. packing the clothes/uniform you're going to put on in the morning inside means it's much warmer when you have to leave your nice warm bag and venture out into the cold.
The heat loss through the head is a long-standing myth and nothing more than a myth.
http://www.guardian.co.uk/science/2008/dec/17/med…
I've always thought that the heat loss through the head might be a myth as heat loss occurs through evaporation (sweating) and conduction/convection so it would depend very much on the size of the areas exposed to cooler temperatures and the head is not a particularly large area of the body (there are certainly larger) – I agree with the Guardian and add, to this extent, that a possible reason for the myth is that the head is less likely to be covered than other areas of the body (modesty being a major factor) so heat loss is likely to occur for that reason. Interestingly, a friend of mine raised this point – heat loss can occur through the capillaries near the skin (as in vasodilation) and there is a greater concentration of capillaries in the head so that could influence the speed at which heat is lost through the head area. I'm no doctor, but that sounds accurate…
Chris' point (and he should know – snow holes being a favourite of his) about some light exercise and eating (especially nuts etc) just before you get into your bag (or whilst in it) is a tried and tested method that most hillwalkers use in the UK as the act of digestion burns calories which, in turn, produces energy and has the effect of heating the body so I agree with that whole-heartedly. Have to say I'd never sleep naked in my bag as I will tend to sweat a little and this would have me sticking to the damned thing all the time! I also found in Sweden a few years ago when the temperature dropped to -6C, which is about as low as I have gone for some time, that my 0C rated bag was fine when I wore all my clothes but there was a substantial difference when I did not wear a hat and socks. I find that a 0C rated bag suits me for a wide-range of temperatures (WM Summerlite, in fact) and can be supplemented in al sorts of ways – silk liner, base layers, down/primaloft jackets, hats etc. This permits me the greatest flexibility with one bag which weighs only 580g (well, mine does, despite the manufacturer's listed weight!)
I always sleep with a hat on. I thought it was to keep warm, but it also blocks out daylight/twilight. As you say, you can easily extend the range of a sleeping bag – I have been thinking about doing this recently with a 40 degree bag I bought this year. Just wearing all of your clothes, especially your rain gear will do the trick. The rain gear acting as an approximation of a vapor barrier.
Didn't know about the vapor barrier so thanks for that. My silk liner has a very nice feel (especially in dortoirs in Alpine refuges) and is also very helpful in increasing the warmth of the bag as well as regulating my sweat. Cannot quite tell you how it does this latter but it's pretty good in winter.