Why Winter Hats are Unnecessary, Yet Nice to Have Around
I, for one, gladly admit that sunny Southern California has no justifiable reason to complain about its annual rainy day, specifically in relation to the experience I’ve had since deciding to spend the better part of each year in New Jersey. Nonetheless, I had a mother. And my mother, being a mother, told me to wear a hat when I went out in the ‘cold,’ because, apparently, that’s where the body loses most of its heat.
Sorry, Mom. I hate to turn this into an “I told you so,” moment, but that “fact” was exposed many years ago for the physiological fallacy that it is. In fact, an article published in the British Medical Journal (BMJ) explains that the belief was probably inspired in part by an archaic U.S. Army Field Manual that recommended covering the head, claiming that some absurdly disproportionate percentage of body heat is lost therefrom. The BMJ cites this article in the New York Times, in which the explanation becomes apparent. For whatever reason, the study from which the army manual extracted its figure was performed on subjects who were wearing arctic gear covering their entire body from the neck down. In other words, these subjects experienced the greatest amount of heat loss from their heads simply because everything else was insulated in army-grade cold gear.
A more recent study, one performed with infinitely more reasonable testing procedures, confirms results that were already pretty well known. Generally, total heat loss in the human body is proportional to the exposed surface area. Since your head doesn’t really have the same square footage as, say, your torso, your head does not dissipate heat faster than your torso does – in the absence of confounding variables, like selectively positioned insulation, that is. You shouldn’t expect more than 10% of your total body heat emission to occur through your head, in the conditions mentioned above.
However, I don’t mean to argue that you shouldn’t wear hats this winter – let’s face it, I am writing from New Jersey, after all. Even the more recent study on heat loss mentioned above noted increased core cooling rates when subjects’ heads were exposed to cold water, regardless of whether or not the subjects were wearing body-insulation. Furthermore, the writer of this article from The New York Times notes that the human head – the face in particular – is more susceptible to sensing changes in temperature than other parts of the body. Thus, protecting these areas would probably allow you to feel a little better this winter. Maybe in some cases, Mother does know best…
That being said, it’s still a scientific inaccuracy to claim point-blank that the human body loses most of its heat through the head, as there’s no physiological property that makes this so. It’s only true for those of us who have dashed out the door donning parkas and snow pants, only to realize we’ve forgotten our hats.