Well you are welcome to give it the ol'try! but you would be better off with a wool sweater. - its all about basic insulation. You are trapping air against your body to provide warmth. The smaller the fiber the more compact, the better it traps air. Fleece (Polar Tec) makes wool obsolete -its fiber is smaller than human and sheep hair and traps better, and is lighter. Duck Down is smaller and lighter than Fleece.
There was an Old Man with a owl,
Who continued to bother and howl;
He sat on a rail, And imbibed bitter ale,
Which refreshed that Old Man and his owl