I'm encountering, anew, the "your warmer in your bag without layers. even naked". I really am having a difficult time posing a clear, concise, CONVINCING argument for this theory that, even I, naively espoused many, many years ago.

We can leave the mattress out of this for now... no wait, lets include it. Sometimes people need to learn the hard way about air mattress' vs. closed cell and insulated mats, but a good argument would save the cold sleepless night on the NeoAir or, worse, those inflatable coleman car camping mattress'. I encountered a strange "air is the perfect insulation" statement a while back. They may have had double-paned windows and a vacuum thermos in mind.

I'll add my own arguments later. For now I just want to get this out and gather some thoughts before I have to face this again with my tour group heading out in the morning on the Salcantay Trail to Machu Picchu. 4 cold nights with a lot of multi-national campers insisting on baring it through the night.

chao,
-michael

I think this occurs when folk have a tight bag, and tight clothing. Restricted blood flow will leave you feeling cold. If everything is sized properly, then it's a no brainer.

And when clothing is dry. If people sleep in damp clothing they can be colder than if they take it off. But obviously the thickness of dry insulating layers, whether clothing or sleeping bag, is what matters.

I would explain it this way:

Air is an excellent insulator compared to water or metal. Air works great if it can't circulate and transfer heat to the cold air or ground. That's why we put feathers or fibers between our warm skin and the colder air or ground, stopping the air from circulating and acting like a heat conveyor belt. "Cold" is not a force, there is only more or less heat (energy), and the tendency is to transfer heat to the colder material until everything is the same temperature. We don't want our bodies equalizing temperature with the colder air or ground. We use feathers or fibers for creating a greater distance between our warm body and the colder outside air, and they are flexible, light weight and can be compressed for storage. More layers make it harder to transfer the heat, with "dead" (non-circulating) air trapped between each layer and the thermal properties of the fabric used. In clothing, it needs to transfer moisture as well, along with being flexible and sealing at the edges, and we use materials that are poor conductors of heat. More layers equals more distance between warm and cold, as well as more trapped air.

My experience has been that if I am cold in my bag and I put an extra layer (that is dry and clean...) I always warm up.
The converse is also true. Often I have a layer on at first, for half an hour to one hour, once I warm up and start to feel that I may sweat I take it off.
I also think that people confuse their findings by wearing dirty and or wet or too restrictive layers, particularly tight socks.

Try it at home. Put your sleeping bag on top of your bed.
Use one for warmer temps than you have or leave it open.
Wear some clothing, get inside/under the bag. Wait for half an hour or so and then take your clothing off.
Wait for half an hour, put your clothes back on. see what happens.
BTw, as I mentioned before , I used the WM Summerlite down to around -5c -7c .
There is no way I could sleep inside that naked at those temps.
(I had wool tights and wool T top as well as puffy pants and jacket on...)
Franco

Edited by Franco on 11/12/2011 14:47:52 MST.

- as noted above, it depends on yr bag ... if yr bag has a lot of dead space, then filling up that dead space will improve the insulation

- depends on what you mean by "layers" ... wearing base layers of fleece theres no real concern as the warm air can move easily IMO between the body parts ... but once you start sleeping in shelled puffy jackets, i think you lose something as each limb is independently insulated ... think gloves vs mitts ... personally i want the warmth of my body to also warm up that of my arms,legs, etc ... you can do this my simply using yr jacket as a quilt inside or outside the bag ... little kids know this as everyone has seen kids in jackets with their arms inside the body and the sleeves empty looking like fu manchu

- depends on moisture ... IMO wearing damp clothes inside yr bag is a very bad idea in cold humid climates ... there have been several threads on BPL where people wore damp clothes to sleep and woke up with a wet bag .. the basic fact is that insulation works best when dry ... why anyone would want to bring damp puffy jackets inside a down sleeping system is beyond me ... i will bring in damp down jackets into a synth bag, but then synth dries much easier and is less susceptible to moisture

- generally you want the best insulation to be closest to you ... i think everyone will agree that it makes little sense to put the least insulating components closest to your body and the best insulating components farthest away ... which incidently you are doing if you wear synth puffies, lower or damp down, etc inside yr bag ... as often the UL down bag is the most insulating and dryest component of yr system

- dew point moisture is an issue should you decide to wear clothing inside yr bag IMO ... again there have been threads where people have down synth clothing or other such inside their bag and woken up with a wet bag .. everyone knows that a synth overbag should go over a down bag, everyone also knows that generally the last layer is often where the moisture will condense in a sleep system ... yet for some reason many people wear their puffy clothing inside their down bags ... in effect turning them into overbags ...

i expect to see a few posts this winter of people getting condensation problems in their bags again ... and i would bet that for many of them the down bag will be the outer layer (maybe with a light bivy) of their system

IMHO, it's pure myth. Layer me up! I'm a darned cold sleeper. I've got an insulated pad and a 0 degree Montbell SS. I'm okay below freezing if I'm wearing a base layer and socks. Done it many times. I know what my limit is.

Recently we "camped" in the backyard at my parents when a family gathering left them without enough guest bedrooms. Hadn't brought my normal camping clothing. It was about 40F. So when bedtime came I just stripped to my undies and crawled in my bag. An hour later I woke up shaking. Debated taking my bag in the house because I was so cold. Was not going to wimp out. Finally woke up the husband, stole his bag liner and wool socks, and slept warm the rest of the night.

So yes, layers help. Bare skin has less insulation than a base layer. What a stupid myth. (That gets told to me by my local gear shop. Do these guys actually get out??)

I don't see why that would make sense. You should be wearing every piece of clothing you have that isn't wet or sweaty when you sleep (provided you don't compress the loft from the inside out). If you wear all of your clothing to bed and are too warm, then maybe you could go with a lighter bag.

I remember long ago telling our then-editor Carol Crooker that one night I had just about every item of clothing on under my quilt. Well, it was a summer UL quilt but it got down to -7 C that night in the mountains.
Anyhow, Carol's reply was that if I had any clothing left over I was not going UL! Yep indeedy.

Cheers

I had this discussion with a guy and his claim on why layers are bad is that the heat from your body core is not able to heat your extremities if its covered up with layers, basically your bag becomes one big happy warm space with minimal clothes. It defies every law of heat transfer I learned in school but there was no convincing. It was a case where you change the conversation to the weather.

Some people just like to buy these apparently counter-intuitive ideas to look like they know something that everybody else don't. We all may fall into that (I have and probably still do :)

The glove vs. mitten case is still valid and it'd be ideal to have a bag that's exactly adequate for the conditions but unless all your nights are the same your bag would be overkill or not enough some of the nights. You can tell your tour group that the same they take layers to face different conditions for the day time, they can (and should) do so for the night time. The basic principle is the same.

The down-to-earth question is: I'm in my bag and I'm cold; I have spare, dry clothes around, what do I do? Do I wear them or not? Some people would prefer to be cold than to accept they were wrong :)

Then there's the cleanliness issue. At home, we use sheets and pyjamas underneath blankets or quilts because it's easier to wash sheets or pyjamas than it is to wash the thicker stuff. The same applies in the backcountry. Sleeping naked and without any kind of liner is no good for a bag that you don't want to be washing too often.

why not put em on top of your bag or quilt ... plenty of people do it

this isnt a case of not wearing the extra clothes IMO ... but whether to put em on inside yr bag or on top

like i said ... i expect a few more threads this year where people end up with wet down bags ... and who bag is basically the last layer, or those who wore damp clothes inside

I've worn nothing but briefs in a winter bag at -20 F, and layered up at 40 F under a thin quilt. From a purely heat transfer perspective I doubt it makes much difference what you wear assuming the sum total and quality of insulation remains the same. Under quilts I like to wear tops and bottoms because I toss and turn all night, causing drafts all the time.

Concerning heat and temperature (sorry, I'm a physicist, I can't help it): heat is a form of energy, and all matter contains some heat energy. Temperature is a measure of the heat energy contained in matter, and heat moves from matter that is hot to matter that is colder. Heat moves via three mechanisms: conduction (e.g. direct contact with the cold ground), convection (e.g. air motion), and radiation (e.g sleeping under a clear sky). Sleeping gear blocks all three mechanisms. Sleeping pads stop conduction to the ground, down or synthetic insulation breaks up air flow without introducing much conduction, and sleeping under some sort of roof helps limit radiation.

i suspect the group here is missing an important point of better management .. that although the nekked sleeping warmer "myth" might be a travesty of theory, it keeps coming back as "fact" .
why ? why does it keep coming back ?

i think it comes back because i have never spent a cold night sleeping nekked, and have froze my buttucous of many a night with all my clothes on. that's just unquestionable data right there. nekked = warm. dressed sometimes = cold.

now, it is no great stretch of smarts to figure out that on warm'ish nights, is when i sleep naturally, and on AFC nights i bundle up.
but nekked memories are of nice and warm, and bundled up are of miserable and hoping the weather changes.

so : it might be quite exactly correct to say that "i sleep warmer nakked than with all my clothes on". and you can bounce physics off it all day, while the "myth" will remain truth.

as for cold not being a "force", yes , well, in a lab.. sure. is fine theory.
things gets cold enough though, it sort'a gets a mind of it's own and starts hunting you down.

if you ever want to actually solve a problem, one needs look deeper.

v.

I can name two people who were cold but not wet, put on more clothes, and then slept warm.

Can anyone name two people who were cold but not wet, took off their dry clothes, did not add a second person, and then slept warmer ?

If they can't come up with two people, then maybe they are the only person for who it works.

Edited by redmonk on 11/13/2011 14:19:46 MST.

People used to think the Earth was flat too. After many years in automobile repair and computer/electronics sales and support, my take is that much of the public is somewhere around the 12th Century in their knowledge of physics or practical skills-- totally clueless, and stubbornly proud of it too!

One day a co-worker asked me what metals a magnet would stick to. We still laugh about a friend who asked about the Dutch Alps! Those street surveys that Jay Leno does scare me to death.

If this many people agree, something isn't right.

My feet DO stay cold if I wear all my clothes to bed, since the least insulated part
of my body is then my feet, what with thick coat and pants, hood and mitts, but only
socks for my feet. It IS like gloves vs mittens for me.

Also if I start out with all my clothes and am warm going in, I find myself in a pool
of sweat before I wake up to vent. This does make for some cold moments later in the
might. In other words, I do dress down most times to go to sleep.

I usually pull my jacket over my legs like a short elephant's foot to keep my feet
warm to start out the night.

My feet DO stay cold if I wear all my clothes to bed, since the least insulated part
of my body is then my feet, what with thick coat and pants, hood and mitts, but only
socks for my feet.

I try very hard to always remind myself to think about things from more than one angle. Never the less ... here's one simple way to think about that situation.

The outside air is at some temperature. The air near your skin inside your clothing is at some temperature that is warmer than the outside temp (98.6F perhaps? ... not sure about that).

The temperature in between your clothing and your quilt/sleeping bag will be colder than inside your clothing and warmer than outside the quilt/bag. If the clothing offers insulation similar to the quilt/bag then that temp will be more or less half way between the inside and outside temp. This is the temperature that your less insulated feet experience. If the foot's insulation is a lot less than that of the rest of your clothing then yep, they'll be chilled.

I have a terrible time sleeping if my toes, fingers or nose are cold. For that reason, those are the first place I add insulation.

YMMV

"I'm encountering, anew, the "your warmer in your bag without layers. even naked". I really am having a difficult time posing a clear, concise, CONVINCING argument for this theory that, even I, naively espoused many, many years ago."

This is a clearly proven theory that really should not be debated. It has stood many of us in very good stead for many many years, and personally I think it's mean spirited and unfair for a bunch of old guys (including me) to disprove it just because it may not be true.

Essentially my experience as a young(er) man went along the lines of
..Go camping a few times
..Go to Uni
..Meet an attractive young lady
..Convince her to come camping with me (possibly on University O week)
..Lend her my spare (spare) sleeping bag
..Explain to her as she's shivering at night, how much warmer it is sleeping naked, as I now am
..Once I have convinced her of this, and she still fails to stop shivering, gallantly offer to swap sleeping bags
..(Cross my fingers when I promise not to look)
..Finally allow her to persuade me to zip the two bags together when my chattering teeth are still keeping her awake a couple of hours later.

For the benefit of geeky 18-21 year old guys across Western Civilisation who own a tent and a sleeping bag, I think we should cease and desist this thread from here on. (And for the benefit of tour group leaders of multi-national campers who clearly have experience which we do not)

Rod

Ah ha! It's just another men are dogs ploy!

Here's the practical outlook on all this. If you go to bed naked and have to get up to pee in the middle of the night, do you really want to go out there naked? Do you really want to try to put on all your clothes before you get up to pee? Who is going to be warmer? The person who went out to pee fully clothed or the person who went out to pee totally naked?

Another consideration is that when I go backpacking I don't usually take a shower before I go to bed. Even if I'm dry, my skin has a layer of dried sweat on it. This often makes me feel sticky. If my sticky skin touches itself, my brain believes that I'm one of two things (because my brain is daft):
- That I'm wet. If I'm wet, I must be cold. Then I start to shiver.
- That I'm sweating. If I'm sweating, I must be hot. Then I start to actually sweat, become actually wet and get cold.

So I wear some clothing to bed and if I get cold, I add layers inside my sleeping bag to help take up the space and get some of that downy goodness closer to my core. I lay my jacket over my hips and waist to accomplish this most of the time.