Scientific experiment here!: a year ago I won from Ebay.co.uk two sleeping bags from different sellers, a RAB Atlas 500 (500 grammes of down I think) and a RAB Ladakh 1000 (1000 grammes of fluffy feathers I guess).

I had been impressed by my son's RAB Ladakh 600 bag and wanted something decent' for myself.

I had slept in the Atlas in a cottage last Autumn and it was OK, but that was inside a heated building!

Finally I had a chance to test both this past week outside camping in the garden! It was +4 Centigrade at midnight when I crept into the Atlas, and 0 Centigrade when I awoke freezing at 4am! I made a hot water bottle and chucked that in the bag but by 6am that bottle was cold and I came inside to sleep the last 2 hours in my own bed! So much for the Atlas 500 - I'd rate this as a 'Summer only' bag or for temperatures over 15 Centigrade!

Then the turn of the Ladakh 1000 a couple of nights later; again to bed at midnight - what a difference getting in, just as a sleeping bag should be! Bulky thing, weighs 1.98kg (including stuff sack) - the Atlas weighs 1.30kg (including stuff sack). I slept fairly soundly until 8am - just a bit nippy at one stage, same temperatures, +4 at midnight,  0 at 4am. It was quite comfy in the Ladakh and a sort of feeling of luxuriousness, so I think I'll be looking out for one for my girlfriend...

It did occur to me that one could put one sleeping bag into another, eg one Atlas into another Atlas... will have to try it. Off to northern Norway in a couple of weeks where it's around 3 Centigrade at the moment, that's why I'm thinking about NOT freezing in my tent!

Very strange about the Atlas, all the reports we have had back about the use of the Atlas 500 have been extremely positive.

Anyone else had experience of using these around 0?

If the Atlas was used, and/or had been stored compressed, it could well have lost a lot of its loft and may need professional cleaning?

Looking at Rab's website the down in the current Atlas models is fill power 560+, meaning fairly cheap and cheerful as down goes, so your experience is not totally unexpected if you are a coolish sleeper.

Zubald's point about cleaning is a good one: dirty down won't loft so well, and works much better once it's been cleaned.  Franklins of Sheffield are Rab's suggested cleaner, and mine as well: they do an outstanding job.  Storing down compressed doesn't actually cause it problems unless it was damp when stored.  It's best to store it loose just so it can stay aired and you can be sure it won't be damp, but compressing it shouldn't be a problem in itself.

The point about the down quality is also fair enough: rab rate the current model at -5C, and that'll be a clean one, plus different people sleep happily at ratings different from the "official" ones (I know people who used a 4/5 season winter bag rated at -25 C in pleasant summer conditions and claimed it was the only time they'd been warm in a sleeping bag, I used the same bag over a 7 year period and only got the zip done up all the way once, eventually sold it on as I found it too hot to be useful).  The Ladakh uses better down than the Atlas so will be aermer at the same weight.

As for putting sleeping bags into sleeping bags, it tends not to work well as it restricts the baffles and prevents the down from lofting properly so it can't do its job.  A case of 1+1 coming in at a great deal less than 2.  A fleece liner will help, as will wearing warm PJs, but a staright-out warmer bag is a better way to go about it. 

Pete. 

Cotton's okay, but silk is lighter, packs smaller  and warmer for the weight, dries out quicker if you wash it and if you do sweat overnight retains less of the result.  Costs more of course, but it is better...  Not all silk liners are created equal: the lightest ones are more expensive but while chepaer ones are heavier and bulkier they are typically warmer too.

Pete. 

I have tried liners but IMHO you are better off with another base layer or a warmer bag. 

Liners tend to get in my way, wrap around my neck etc usualy when I need to get out in a hurry.  The bivy bag adds warmth but this seems silly to me due to cost and weight. Of course if you  have one go for it, give it a go.

I would look at your sleeping mat as well as down bags do not generaly insulate you as well as synthetic ones.