As Robin says, as long as it's in a liner inside the bag. I just use a cut down garden Sack, and assuming you are using a tent, a bag is fine. I am assuming you mean down. 11 crossings, all using a down bag, never been wet in one, or had one wet.
My current choice is a down quilt, that goes down to 10 F if needed. So you will be fine.

Choice of bag? Well, dear is cheap. My own take would be to go for a custom PHD Click here to take a look They are the dogs. They made me a custom sack back in '99 which is still mint after 18 ears in the High Pyrenees.

Robin and Andrew are right on the money. Keep yr down dry and it's yr sweet friend after a hard old day!

And that's the kicker. Never let yr bag get wet! And go for 900 fill-power down.

Moving on from from this - there's a whole train that gets the need to have a warm and dry set-up that stands aside from your daily. What this be? Simples - take the very worst you can imagine - horrid driving wind/rain/sleet/snow. And now you get into yr shelter - remembering to leave all that wet stuff in the porch, yes? And now you dig into yr pack and bring out all that sweet dry down, (bag, footsies,
whatever), fire up the stove, guzzle down the grub and all is well with the world.

Down can work out cheaper in the long run as it is more resilient to compression than synthetics (although you should always store down sleeping bags loose when not using). You can restore a down sleeping bag to virtually new condition by using a specialist cleaner like Elite Cleaners in Rotherham. A good down sleeping bag/quilt will last a very long time. Synthetic sleeping bags lose their loft after a few years with constant compression, although they are improving with new materials (e.g. Climashield Apex). Down bags also compress smaller in your rucksack.

If you look on backpacking forums, you can often pick up a good down sleeping bag cheaply. I bought a Western Mountaineering Ultralite for less than half price the original price a couple of years ago. Although it was in excellent condition, I had it cleaned. Effectively I ended up with a new sleeping bag for a song. Western Mountaineering is widely regarded as the Rolls-Royce of sleeping bags, so it's well worth having a look around.

thank you all so much for your helpful information on sleeping bags....there are so many to choose from !!!

wendy

Hi Wendy,
I've used a light down quilt (PhD) with a Pertex overbag (homemade) for several years, so my sleeping "bag" weighs about 700g. Keeping the weight low is important and this system works for me. Don't be shy of sleeping in all/any dry clothing as well if you are cold! In the last 6 years I've always woken up at least one morning to find frost and/or snow on the tent.

You should really try sleeping indoors once in awhile Kirsten ....

Hi Wendy,
It's my first time too and I'll be using my Alpkit sleeping bag.
When I started wild camping about four-five years ago I bought a basic Alpkit down sleeping bag. I love it. It is fairly warm (they do make warmer ones than mine), although I don't use it in mid-winter and it is still in great condition. I got a short version, which means I don't have to carry round extra material! It was also a lot cheaper than many of the other options such as Rab, etc. So far everything I've had from Alpkit has been great and delivered fast - you can only order online but they don't charge extra for delivery.
See you in May!

I always carry it in a dry bag so it doesn't get wet!
But then I carry everything in dry bags whatever the weather so none of it gets wet :)

Hi Jessica, thanks for your information about sleeping bags, I have been on the site to have a look at them. Hope to see you to in May.
Wendy