Sleeping in a sleeping bag by (really) cold weather can be very nice ………… provided you do not get cold! Here are some tips to be sure of a good night’s rest, during a camping shelter under the stars or under a tent.



We have classified the tricks for not being cold in his sleeping bag according to 4 categories:

  1. The essential
  2. The simple and free
  3. The paying
  4. The false good ideas


1. The Essentials

  • Opting for the right sleeping bag: not necessarily the hottest, or the most expensive, but the one that will be adapted to our needs (eg sleeping bag in dry weather, synthetic in wet weather, etc.). Find out more: How to choose your sleeping bag?
  • Ensure the correct size of the sleeping bag: a sleeping bag that is too small will cause a cold sensation in the feet and head, and a sleeping bag that is too large will require more volume to be heated.
  • Be careful not to wet your sleeping bag during a rainy day: garbage bags, plastic bags, sea to summit bags, etc.
  • Sleeping on an inflatable mattress, type Nemo, Therm-a-rest: a large amount of the cold felt comes from the ground. A mattress of good quality allows us to isolate against the terrestrial cold.
  • Wear merino wool undergarments (the same ones used during the day).
  • Cover the extremities (bonnet, socks, and gloves in merino, or classic wool): in extreme cold, the body concentrates its contribution of heat on the vital functions (thorax and brain), to the detriment of the extremities.

2. Simple and free tricks (or almost)

  • Remove the sweat/grime of the day: even if it is cold, to clean or to wash allows to assure a better breathability for our skin, and thus better heat exchanges for the night.
  • Keep the (precious) heat: do not wait to get cold at the bivouac to get dressed.
  • Mounting a small windproof wall (stones, talus, snow, etc.): in addition to isolating against the wind, it is a great way to …
  • … raise body heat (but not too much, not to perspire). Also think of doing some exercises before going to bed (flexions, pumps, reels, jumps, etc.)
  • If it is possible and allowed (and not dangerous), make a fire nearby. Beware, however, of wind and twigs which can ruin the tent, sleeping bag, sleep, forest, etc.
  • If you sleep in a tent,  tighten the outer fabric so that it does not touch the inner fabric (insulating air layer).
  • Eat a light and digestible meal in the evening before going to sleep: the digestive system takes up a lot of energy (so calories) from our bodies to digest food. So eat enough, but not in excess, and eat hot if possible.
  • Drink a hot beverage before going to bed: sweet tea, etc.
  • Do not dress too much in your sleeping bag:   merino wool underwear is enough (long-sleeved t-shirt, 3/4 sticky or long, socks, hats, gloves). If we get too hot, we sweat, we wet our sleeping bag, it no longer plays its role, and we are cold.
  • If there is too much space in the kidneys or abdomen, put a jacket open under or over itself in the sleeping bag.
  • Thoroughly close the sleeping bag to prevent cold drafts: zipper, shoulder collar, elastic tightening hood. Only the mouth and nose should be in the open air.
  • Have mouth and nose in the open air: not to create condensation inside the sleeping bag.
  • Drink a hot drink during the night: sweet tea, etc.
  • Do not refrain from urinating: in addition to causing stomach pains, even kidney problems, refraining from urinating consumes calories (heat) for nothing. Gentlemen, to avoid getting out of the sleeping bag, arrange a container nearby (be careful not to spill it …). Ladies, know that you have all our compassion because you will probably be obliged to leave the sleeping bag, unless you use a “piss-standing” (or female urinal).

3. Paying Tips

  • Use a soft bottle in its sleeping bag: the good old remedy but still works!
  • Use a (real) “meat bag”:  Thermolite Reactor sheets are light, warm and practical, which improve the temperature of your sleeping bag by +8 to + 15 ° C. It would be a shame to deprive it 😉
Depending on the bag chosen, the Thermolite Reactor technology increases the temperature of the sleeping bag.
Depending on the bag selected, the Thermolite Reactor technology increases the temperature of the sleeping bag from 8 to 15 ° C …

4. False good ideas

  •  To stack all the layers of clothes that one has:  nothing to prevent the body heat to breathe to the sleeping bag, and thus to play its role of regulator …
  • Sleep naked:  this was valid 50 years ago (and still) when we had only wet cotton to wear. Even if you have a lot of hair (:-), merino wool underwear will be much more suitable …
  • Use a silk bag sheet:  contrary to popular belief, silk does not keep warm. On the contrary, it allows refreshing the skin …
  • Wrapping your sleeping bag in a survival blanket:  nothing to create condensation, wet your sleeping bag, and shiver all night …
  • Starting the stove in a confined space (tent): risk of death due to the emanations of carbon monoxide (CO).
  • Gourd food during the evening meal: nothing better to sleep badly (stomach pains), and take up all the energy of your digestive system, the big consumer of oxygen and calories …
  • To drink a whiskey (or gnole, etc.): the alcohol dilates the veins, increasing the feeling of cold in the medium and long term by a loss of heat …
Photo: team Montania, bivouac under tent at Plan de la Lai, Beaufortain.


“… Sleeping outside with a sleeping bag, okay, but without being cold! If this is possible and planned, make sure that your bivouac happens in the best possible conditions in order to have only one desire: to start again! 
Most of the time, simple tricks inherited from common sense make it possible to get out and thus optimize its nights to not be cold. It would be wrong to deprive yourself of it … 
No more excuses, go, outside! But with adapted equipment … 


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