space blanket under sleeping bag?

[Shoki]

Another bit of experience:
I once wrapped a space blanket around my legs and feet inside my sleeping bag for added warmth/vapor barrier on a particularly cold and wet night and the results were less than optimal. I fell asleep toasty warm only to wake up hours later, overheated and sweaty. I removed the space blanket and fell back asleep toasty warm again only to wake up about an hour later even colder than I was in the first place! I had a miserable night, didn't sleep much at all, and had a sluggish day when I woke up.
I guess the moral of the story is 'Use emergency blankets only in emergencies and bring the right gear in the first place!'

 

[Ravaillac]

Another bit of experience:
I once wrapped a space blanket around my legs and feet inside my sleeping bag for added warmth/vapor barrier on a particularly cold and wet night

Not sure the idea of "partial vapor barrier" makes sense. I'd say it's either completly water tight or useless.

 

[Joezilla]

I've played with the space blanket, hemlock bows, sea grass, bamboo, and got knows what else. The space blanket is the only one I would recommend under a hammock (Grassy hammock = itchy!). On a rock in the middle of winter, I slept soundly with one of these INSIDE my 20 degree bag, only on the bottom, with my pad underneath the bag.The make I'm speaking of is the cheap $4.00 kind. It seemed to regulate pretty good, as it got down to 18 degrees and I was warm. I did not have any sweating problems either. I did not need to bunch my bag up around me, I just kept the skull cap on to keep head warmth. The thermo-regulating qualities of a safety blanket can be explored alot more when you think of them as a shield to keep heat in, so I keep them close to my body. If you think you are sweating (some how, I escaped!) , try to make it so that your humid stanky swamp feet breathe a little on top of the bugger rather than wrapped up in it.