Keep the AIR out and the body heat IN. I don't know how you guys can live in such cold weather.
I lived in Germany for four years, cold as #^$&. I've lived in Minot North Dakota for 6 months, never Again !
Lived in Missouri for 3 years, hated the snow. Now in Florida, and love the weather, however, thank goodness for air conditioners in the summer.
In Germany we used big feather bed pillows that covered the entire bed.