Those emergency blankets trap moisture. mylar of any color is not breathable... its a plastic sheet. Sure sit by a fire with this mylar thing?... hahahah thats not from experiance in freezing weather.

Winter camping is a bit more serious than most people think, thus so many SAR calls n fatalities as a result of being unprepared. skimping on equpment is not advisable for winter camping. Take enough clothes n equipmnet to spend a night in sub freezing weather. Those mylar blankets are fine after the marathon, but its not meant to be used for winter overnight camping. It may make a nice wind break but to sleep in it is nuts. Next time you go out... take your full winter kit n try the emergency blanket as an experiment first, but not as your primary sleeping gear expecting to cut down weight n save a few more ounces.

That reflective thing is a myth. There is absolutely no insulating factor in a 6mil plastic sheet... all your generated heat is lost as fast as you make it regardless of how much reflective heat it tosses back... warm moist air trapped inside will rob you of all your heat.

wrap yourself in tin foil shiny side in, lay in the fire, baste every half hour n turn for even browning.

happy trails.