Posted by: Gershon
What I've learned about sleeping bags - 09/18/11 11:31 AM
These are my observations and is not expert advice. It's just to stimulate conversation.
It seems like everything has changed in the last 10 or 15 years and sleeping bags seem to be no exception. My old bag is a Coleman I bought in 2001. I spent about 4 months cowboy camping in it without a tent, or even anything to put on the ground under me. It was comfortable and warm down to its rating of 20 degrees and even a bit lower. When it got dirty, I just tossed it in the washing machine. It doesn't seem to affect it.
A chance remark at a store led me to learn that temperature ratings now assume a 1 inch pad and wearing long underwear. Women also sleep colder than men, so they need a lower temperature rating or they should use the comfort and not extreme rating on the bag. So I did some research and found an article by REI which I'll link to later if I can find it again. The tests are done with an instrumented dummy who doesn't move. I find not moving makes me sleep warmer.
In my old Coleman, there is more insulation on the bottom than on top. Newer sleeping bags often have the reverse because of the assumption of a pad. Some bags even have a certain pad that is designed for them.
Now I cacoon my sleeping bag over a hammock. I've been using an Alpine 20. As it's getting cooler, I've been observing cold and warm spots. The hammock holds the sleeping bag just off me and it feels like heat is radiating from it inside and warming me. But if I pull it tighter it becomes cooler. Same if I raise it off me by raising a knee. In other words, there seems to be an optimum size for a sleeping bag. Not too tight and not too loose. For this reason, a side sleeper may be colder than a back sleeper in the same bag as the bag is pressed closer to them.
There is a constant debate between clothes and no clothes. I generally wear clothes because I get up in the middle of the night. I've found there is little difference for me on the bottom. On top, wearing a shirt and a fleece works best for me when it's cold. If it's warm, I won't wear the fleece. Others will have a different experience.
From articles I read, a lot of heat loss occurs out of the top. I'm too paranoid about a zipper getting stuck to pull it all the way up on a mummy bag, so I generally leave it down a bit. Sometimes I'll sleep with my head in the bag. It's warmer and I've never had a condensation problem. Other do have one.
In summary:
When taking another person's recommendation, be sure to know their size compared to you. Also ask if they are a side sleeper or back sleeper and if they use a pad. It seems to make a big difference.
I find a bag that fits closely all around, but not tightly is warmest. For those that are claustrophobic, this would probably drive them crazy.
Personally, I wouldn't buy a bag now without trying it on. Temperature rating doesn't seem to tell the whole story.
It seems like everything has changed in the last 10 or 15 years and sleeping bags seem to be no exception. My old bag is a Coleman I bought in 2001. I spent about 4 months cowboy camping in it without a tent, or even anything to put on the ground under me. It was comfortable and warm down to its rating of 20 degrees and even a bit lower. When it got dirty, I just tossed it in the washing machine. It doesn't seem to affect it.
A chance remark at a store led me to learn that temperature ratings now assume a 1 inch pad and wearing long underwear. Women also sleep colder than men, so they need a lower temperature rating or they should use the comfort and not extreme rating on the bag. So I did some research and found an article by REI which I'll link to later if I can find it again. The tests are done with an instrumented dummy who doesn't move. I find not moving makes me sleep warmer.
In my old Coleman, there is more insulation on the bottom than on top. Newer sleeping bags often have the reverse because of the assumption of a pad. Some bags even have a certain pad that is designed for them.
Now I cacoon my sleeping bag over a hammock. I've been using an Alpine 20. As it's getting cooler, I've been observing cold and warm spots. The hammock holds the sleeping bag just off me and it feels like heat is radiating from it inside and warming me. But if I pull it tighter it becomes cooler. Same if I raise it off me by raising a knee. In other words, there seems to be an optimum size for a sleeping bag. Not too tight and not too loose. For this reason, a side sleeper may be colder than a back sleeper in the same bag as the bag is pressed closer to them.
There is a constant debate between clothes and no clothes. I generally wear clothes because I get up in the middle of the night. I've found there is little difference for me on the bottom. On top, wearing a shirt and a fleece works best for me when it's cold. If it's warm, I won't wear the fleece. Others will have a different experience.
From articles I read, a lot of heat loss occurs out of the top. I'm too paranoid about a zipper getting stuck to pull it all the way up on a mummy bag, so I generally leave it down a bit. Sometimes I'll sleep with my head in the bag. It's warmer and I've never had a condensation problem. Other do have one.
In summary:
When taking another person's recommendation, be sure to know their size compared to you. Also ask if they are a side sleeper or back sleeper and if they use a pad. It seems to make a big difference.
I find a bag that fits closely all around, but not tightly is warmest. For those that are claustrophobic, this would probably drive them crazy.
Personally, I wouldn't buy a bag now without trying it on. Temperature rating doesn't seem to tell the whole story.