I have heard that you should sleep in the buff in a down bag to optimize its insulating ability.and that wearing extra clothing actually decreases its rating.any comments regarding this?

>I have heard that you should sleep in the buff in a down bag to optimize its insulating >ability.

Yes-this is absolutely true. Also remember how important it is to zip your bags together to avoid frostbite. That's how all the pros do it.

Just show those co-eds this post if they still don't believe you.:)

As David says, that propaganda line was developed by male college students along with such familiar phrases as "Trust me." Some still believe it! I don't know if any females have tried this particular line.

In reality, the more insulation between you and the cold air, the warmer you'll be. The exception is when there isn't enough room for the warm clothing inside the sleeping bag, and the insulation of both clothing and sleeping bag is compressed and can't fully loft. In that case, you will be colder. The solution is a sleeping bag wide enough to fit over all your puffy insulated outer clothing without compressing either the bag or the puffy clothing.

Standard lightweight backpacking practice is to get a slightly less warm bag than needed and wear your insulating clothing inside, which will take it down another 8-10 degrees F. It never worked for me. I never realized why until the EU's EN13537 ratings came out--the "comfort" level for cold sleepers/women (like me) is about 9*F higher than the "lower limit" rating for warm sleepers/men. It therefore seems logical, after all, that I have to start putting on more clothing at the "comfort level." At the "lower limit" I start getting cold even with all my insulating clothing on. That 8-10*F turns out to be about right after all!

The testing for EN13537 ratings is done with a dummy wearing base layer top and bottoms and a knit camp, and sleeping on a 1 inch foam pad. In other words, the technical folks who developed the standards don't believe that line about sleeping naked, either.

Edited by hikinggranny on 12/10/2012 00:01:15 MST.

You will be colder sleeping in the buff than sleeping with extra clothing, unless as Mary pointed out, the bag is so small that the only way not to compromise the loft is sleeping in the buff.

If that is the case, then you bought the wrong bag.

Edited by Sparticus on 12/10/2012 00:26:16 MST.

If the choice is between sleeping wearing sweat soaked and dirty clothing and naked, pick naked.
Otherwise any clean and dry layer will work best.
I have had this discussion several times and it really is very simple to verify.
Go to bed wearing some thermal clothing.
After half an hour or so , take them off.
Do you warm up or cool down?
Just to confirm the next night (at home ...) go to bed naked.
Wait half an hour than put your thermals on. Do you cool down after that or warm up?
Well it works exactly the same way in the bush...
BTW, feel free to put you mat down on your floor and sleep inside you sleeping bag if you want to make the test a bit more "real"...

Edited by Franco on 12/10/2012 00:35:02 MST.

David forgot to mention that once you've zipped your two bags together you should make sure that you fit three of you in there, in the buff. Maximum body heat, minimum dead air.

Simple laws of physics make it obvious why extra clothing would help not hurt. No further testing needed.

Maybe the metabolic level is higher with no clothes and two people which makes up for any insulation loss?

it depends ...

1. if your clothing is damp then all that moisture has to go somewhere ... itll end up in the last layer of your system ... ie your bag

2. a down bag as the last layer can leave you susceptible to condensation issues, especially if you are wearing synth puffy clothing inside ... body moisture migrates to the last layer ... and that is your down

3. the more insulation the better all other things being perfect so having the clothing insulate somehow and being used would be warmer

4. in such cases you can always put the puffy layers OVER your down bag rather than inside ... which youll basically need to do if they are damp anyways ...

now a synth bag ... just sleep in it ;)

Edited by bearbreeder on 12/10/2012 10:51:03 MST.

Love getting layered in the sleeping bag.

This post is degenerating. I love it.

"This post is degenerating. I love it."

+1

First spooning, now "layering". Where will it all end? BPL is becoming a moral cesspool. Sigh, guess I'll have to head over to WB. :@(

"2. a down bag as the last layer can leave you susceptible to condensation issues, especially if you are wearing synth puffy clothing inside ... body moisture migrates to the last layer ... and that is your down"

Eric,
Please explain how wearing clothes or not will impact condensation? In both scenarios with and without clothes the down bag is where the dew point is likely to occur if it occurs within the sleep system. Don't see how that will be impacted when wearing clothes unless you layer up so many layers that the dew point moves to your clothing. But that is highly unlikely.

body moisture will migrate to the last layer, and tends to stay there ... that will be the down bag ... where the dew point will possibly be ...

which is why people uses SYNTH overbags, not down ones ... and why several people have experienced issues here when using synth puffy clothing/bag under a down bag, instead of vice versa

I think moisture will evaporate out of the bag

Except, if it's below some temperature (20 F?) then there will be a place in your insulation where it goes below freezing, and at that point the water will freeze, and then not evaporate out of the bag

well lets ask 2 questions

1. if you have 2 bags/quilts to layer ... one synth and another down, which would you put on top and why?

2. other than a snugger more personal fit ... how is puffy clothing different from a bag/quilt?

people can draw their own conclusions ....

What clothing combinations come close to the actual r rating of a synthetic quilt? And if that high r clothing is needed to stay warm then the alternative of not wearing it would result in you freezing your apples off. Remember this is a direct comparison of clothes or no clothes with the same down bag. Yes,'re right people can draw their own conclusions.

Edited by gg-man on 12/11/2012 19:58:49 MST.

put the puffy OVER the bag ...

all the positive BPL thinking in the world wont change basic moisture management ... the "R" rating is irrelevant ... people use very thin synth overbags with low "R" ratings all the time to manage moisture

its that simple ;)

Edited by bearbreeder on 12/11/2012 20:04:37 MST.

So you honestly believe that you are going to sleep warmer with a puffy on top of sleeping bag instead of wearing it. Really? I will keep doing it wrong!

it depends how you size the bag and the conditions ... a bag that gets damp aint that warm ;)

ask yourself why you are letting the moisture migrate to the outer bag layer ... the bag is the most important thing to keep dry ...

Edited by bearbreeder on 12/11/2012 20:11:47 MST.

I am totally with Greg on this one. I usually layer in a bag when it's cold. Typically, when it's really cold (during 3-season backpacking) that includes long underwear, warm and dry and clean sleeping socks, the clothes I've hiked in, a down jacket and a balaclava. Sometimes my breathable rain jacket, too. Inside a down bag. And I've often worn synthetics inside a down bag. If it's a problem, I've failed to notice it. I HAVE noticed that I find layering is warmer.

Like layering clothing alone, it might take a little practice to figure out what works best. A good fit between all layers is important. I prefer to wear my insulation rather than lay it on top of my bag, because I move when I sleep. I don't wear soaked clothing in a down bag. I avoid getting sweated up just before or during bedtime.

Edited by Colter on 12/12/2012 15:34:01 MST.

They key here is insulation - and indirectly loft.

What I do is if the clothing isn't compressible, I wear it. My smart wool long underwear is a good example.

If I have down pants or a down jacket. I usually lay it on top of my sleeping bag which holds in additional heat.

I use a hammock so I have an under quilt/top quilt combo.

The other thing I need is some sort of wind shell for my under quilt ... the tarp doesn't TOTALLY work out for me.

So what is the answer to Eric's question #1?
Inquiring nekked spooners want to know?

I always wear clothing in my sleeping bag. This is an ultralight backpacking forum. If you want to be as light as possible, you should wear every single piece of dry clothing you have to bed. If it gets too warm for that, then you are carrying more weight in your sleeping bag than you need. Obviously that's hard to get perfect and temperatures can vary unexpectedly.

ahhh ..... but what if it gets colder than expected ... just suffer ?

;)

there people yakking about carrying UL camp chairs around here, no "true" UL BPLer needs a chair ... i doubt an extra few oz to stay a bit warmer is gonna kill you ... not having that extra bit can be quite detrimental to your happiness though =P

susan ... hint ... if you want to maximize warmth, be the spoonee and not the spooner ... dont ask me how i know that =P

there are several threads if you look around where people put down over synth and ended up with wet/damp bags ... it depends on the conditions, but if you do find yourself with a damp outer bag thats one of the possible culprits ...

Edited by bearbreeder on 12/23/2012 20:00:28 MST.

dont ask me how i know that =P

Bearhugging? ;)


You guys are talking two different things. Cold vs wet and cold.

the wetter it is the more important synth on the outside is. If its dry and cold it doesnt matter as much- unless you are sweating then it turns back to wet and cold. (and drop a layer and it wont matter anymore)

eric is from PNW- always wet so he defaults to thinking that way. (me too)


That being said i sleep in synth clothing in my down bag.

(Do as I say, not as I do) :P

mmmm ... bears are sooo warm ;)

i think its better to say that i default to absolutely and utterly keeping your down sleeping bag dry .... i use more a synth bag these days so its not a concern as much ... but IMO down must be kept dry no matter what, especially any bags ... everything else can be a sacrifice to the BPL gods ...

INSIDE LAYERING:
> polyester long john tops & bottoms (thin or expedition wt., depending on temps)
> insulated jacket & pants (down or synthetic fill, like Climashield)
> heavy "sleep socks"
> balaclava (THE most important part of inside layering)
> thin glove liners (you learn this really helps)
> Hobbit "Second Dinner" before bed to fuel the furnace (& "layer" on more fat ;o)

OUTSIDE LAYERING:
> "bag topper" down mummy shaped that covers the top & sides and attatches with Velcro or summer quilt over yer bag
> Rain parka zipped up and put over the foot of the bag (keeps bag exterior dry too)
> thick layer of dry leaves under your tent floor or groundcloth. (works very well)
> bivy sack
> tent or fairly closed down tarp

NOTE: For very cold winter camping you may need a face mask too. Noses can get uncomfortably cold.

Edited by Danepacker on 12/30/2012 13:10:33 MST.