The rating on them is a survival rating, from what I remember. Seems like it's for 4 hours or so as well, and not "all night". My son and I have two sets between us, and while heavy, they will certainly keep you warm. I have since purchased down quilts in an effort to lighten my load, but he still uses his (both the green and black together with a synthetic UQ). He does not get cold. We haven't been below 20 degrees, though. We are still using Milsurp packs, so his fits in the sleep carrier fine. I'm not sure what he's going to do when his ULA Circuit gets here in a couple of days