All I know is that when I shaved my head or keep it really close cropped, any type of hat regulates body temperature really well. Anything from a cotton cap to a wool watch cap. Think about it, when the body starts to cool down it restricts blood flow to your hands and feet and other extremities. It puts more blood flow to the head. If your feet are cold put on a hat works because the heat loose through your head is now slowed with insulation, more heat is retained, so more blood can now be reapplied to the extremities. And yes, you can loose alot of heat through your head, but it is amazing what a 1/4 inch of hair will do to slow that transfer down.