Originally Posted by
leaftye
Both for me. Try sleeping next to a lake at that temperature, and I'm sure it'll happen to your bag too. It's not guaranteed that you'll notice though. It's almost impossible to tell if it's happening unless the shell is translucent enough to see the down sticking to the underside.
This is where a VBL can really help. A couple pack liner bags can do the trick. Rip holes into one to make a sleeveless shirt and pull the other one over your legs. I've used this to thoroughly dry out my bag with great success.
Imo you are still in the theory world when you say you might not notice. I spent 20-30 days camped next to lakes and creeks at least every other night in the Sierras two straight years. I also used the same down sleeping bag for over 100 straight days (minus the occasional hotel). I'm certain that my sleeping bag absorbed a little moisture but I didn't notice a loss of insulation. If this isn't going cause problems then I think you are talking from a purely theoretical standpoint. I think your argument applies more to winter camping where the sleeping bag absorb moisture at night and it freezes in the bag and it continues to happen night after night.