Wool Blanket

For some extra protection on those late season or winter nights in the wilderness, toss a light wool blanket over your sleeping bag when you sack out.  Besides providing another layer of trapped air, which is the key to insulation, it draws away the body and clothing moisture that has pushed to the outside of your sleeping bag.  This can accumulate as dampness or frost that reduces your bags efficiency, especially over the course of a few nights, and especially if the weather or your activities don’t allow you the opportunity to dry it out.