It sounds a common sense that we lose much more heat through our heads than the other body area. However, according to a 2008 report in the British Medical Journal, we only lose 7 percent to 10 percent of our body heat through our heads if our heads are uncovered while the rest of the body is covered.
Why did we have this misperception? It was because our heads and upper chest are almost five times more sensitive to temperature changes than other areas of our bodies. These areas are densely packed with blood vessels and nerves. There is far less subcutaneous fat on the head to act as an insulator than in the rest of the body. The head and chest are sensitive areas, so we may feel cold or warmth more in our heads than the other parts anyway.
So covering our heads is very important, and the lower the temperatures that we are exposed to, let alone in wet, the more important it is. When we are cold in the wild, our bodies respond in two ways. First, our muscles shiver and generate heat by moving. If this does not work well enough, blood flow to the extremities is reduced. Human uses blood to keep body core and vital organs warm and sacrifice fingers, toes, ears, and noses to frostbite. This is dangerous in the outdoor circumstance indeed.
Another reason that led this perception was due to that human bodies are always covered with clothes even in the warm weather, whilst very often head area might be uncovered for instance no hats on. This feeling particularly is tense when the weather suddenly turns bad in the wild.