If you teach a class on hypothermia in the wilderness, you are bound to be asked about the value of a warm person snuggling with a cold person in a sleeping bag. Actually, "snuggling" may not be the best word, because, putting aside the giggles, it’s not easy or fun to hug a physically cold person. Snuggling is a necessary task, not a recreational experience.
I’ve been told two people in a sleeping bag to treat hypothermia is the “standard of care” in the wilderness. Actually, it’s not. The science isn’t strongly in its favor. The limited research into body-to-body warming says that it doesn’t help much, but also that it probably doesn’t harm.
Myths about Snuggling to Treat Hypothermia
Clothes, or No Clothes? Ideally, the people should be nude. The more skin to skin contact the better. However, realistically, even nude, direct skin contact between the heat donor and the patient is small.
Will Warming Up Make the Patient Stop Shivering? We know that shivering is a powerful means, indeed one of our best tools, to produce heat in a person who has the energy reserves to shiver. But, we also know that warming the skin blunts the shivering response. We don’t know the significance of the shivering inhibition from warming skin because, even if the patient shivers less, they feel more comfortable and preserve their energy reserves (e.g., they burn fewer calories shivering).
Will the Heat Donor Become Hypothermic? I’ve seen heat donors realize that snuggling isn’t a lot of fun, but in the real world donors don’t become hypothermic.
What Happens if the Sleeping Bag Gets Sweaty Inside? We’re often asked about the donor sweating and wetting the insulation. Yes, it can become steamy in there, but in our experience wet insulation has not been a problem.
Pros and Cons
What are the positives of putting another person in the bag?
- You can monitor the patient closely.
- You may help the patient warm while they expend fewer calories shivering and warming the insulation, just like the thermos bottle of the hypothermia wrap.
What are the negatives?
- You may not be able to close the opening of the sleeping bag. The effectiveness of the hypo wrap may be reduced.
- You’ll have the weight of two to carry (assuming you are doing a carry).
- The heat donor is not able to help with other important tasks such as building a fire and preparing shelter, hot drinks, and food.
As always, we’ll use our judgment, understand the principles of treatment, and weigh the factors in our specific scenario when we decide whether to put a second person in the sleeping bag or not.
