Yes. Viesturs also has a commendable reputation for dropping his own plans and aiding other climbers in distress. From the Wikipedia article on Viesturs:

A down bag may not be the best idea if there is a dust mite allergy involved. Allergy specialist specifically told us to avoid foam or feather pillows when he tested me to see what I was allergic to. Don't know if there would be a big difference between a feather pillow & down.

Good points. Certainly you need to verify ratings on any bag. The EN rating is a good one, but, like the US ratings which are made using a different set of criteria, they can be misleading and add up to a mismatched bag. I find the US ratings a little high for me, the EN way too high. I usually need to go one step higher - using my usual setup. My Daughter-in-Law is a totally different story. She needs a bag warmer that the EN rating to stay comfortable. She uses a US rated 0F bag in 40F weather. At 35 she needs to add a dog (thankfully she has one that likes to sleep with her).


Respectfully,

Jerry

An article I found, Degrees of Comfort has a good summary of correction factors one can use to more closely figure out the temperature rating they should be looking for in a bag.

Interesting article. One other thing I noticed on the really cold night of camping was the air inside the tent also got really cold, so simply breathing in the cold air seemed to sap the heat right out of me. Added to that, every time I moved cold air seemed to rush inside the sleeping bag (or the air I had warmed with my body rushed out, either way, brrrr) made the night really miserable, even with 3 layers of clothing on. Dry synthetic long johns, fleece shirt and pants with wool socks and a hat on my head, and I eventually added insulated coveralls to get through that night (and yes, all were fresh and dry). How cold did it actually get? Hard to say for sure, i know it got below freezing as there was frost on the cars, tents, equipment, grass, and everything else that was outside the tents.

A few other things to note, the sleeping bag I used is a rather normal rectangular design, seemed well insulated tho it is an older bag we bought a while back so I suspect it's rating was less than adequate. DS and I slept on 4 layers of old comforters (2 blankets each, folded in half) with the sleeping pad on top of that, followed by a fleece blanket and then the sleeping bag (with two of those chemical handwarmers inside) on that, with the foot of the sleeping bag covered with a large contractors bag and all covered with more fleece blankets. DS seemed to tolerate it better than I did, and with temps expected to be close to the same for the next weekend's campout, I went and bought us some cots to sleep on, plus the fleece sleeping bag liners and the full size chemical hand and body warmers. I guess it was a combination of all of those and maybe the temps not getting nearly as cold, but that next campout, with the same sleeping bags and blankets we had at the previous one, was much more tolerable.

A good mummy bag would definitely solve that particular issue. When its cold out I find its best to cinch the hood up nice & tight, leaving only a breathing hole. This keeps most of that nice warm air inside the bag where we want it!

Something like this:

The perception of cold, like that of pain, is absolutely an individual one. What is comfortable to many, if not most people, may be unbearably uncomfortable to others. A large number of medical, genetic, and/or environmental conditions affect these things---too many to list or even try to identify.

The only solution is to try to gauge the individual's own susceptibility to the precautions and equipment in your planning.

As an example, I tend to wear a sweater and/or long sleeves when many around me are in short sleeves. . . .I am one of those who need those "warmer" sleeping bags.

Your illustration shows the warmest way to wear a mummy, but i am always twisting and turning and thus breathing into the bag, etc., and it gets to be quite a hassle. If it isn't bitterly cold,I like to cinch the bag around my neck and put on separate insulation around my head and neck. A balaclava works great for that. Then I can flop around all I want.

No one has mentiond that sleeping in a group makes a difference, such as being the middle person in a three person tent.Mild exercise will warm you up if things get really cold....

For me, the best sleeping bag is sleeping on my mattress at home. I am side sleeper and nothing has ever been comfortable. Add to that, I am claustrophobic. If anything gets the least bit twisted or constricting, I go absolutely ape! I usually run out of the tent in a cold sweat, partake of a good Modified Stationary Panic (thanks Patick F. McManus), and then sit by the fire until I calm down - 20-30 minutes. So, I have to sleep, how shall I say it, fairly close to birth conditions - only socks and underdrawers. In the end, I don't do the sleeping outside thing anymore.

As has been discussed here before, you need to pick the right bag for the conditions. I live in a fairly wet area, so I choose synthetic bags. We also do not generally get extremely cold. I also have fairly young scouts, so the durability and safety factor of the synthetic bag is a plus for me. If I lived in a dry climate I would prefer down bags. It is always a challenge to equip the scouts suitably without overloading them. I have a good 0 F down bag, and my own sons each have one as well. Cost is also a significant factor for many families, which also leads me to the military surplus synthetic bags. You have to find what is right for your situation, there is no one right answer for everyone everywhere.