Is it true that up to 45 percent of your body heat is lost through your head? Apparently not. The British Medical Journal reports this week that this myth has be debunked by researchers at Indiana University. The medical myth was traced back to advise published in a US Army Field Manual from 1970 which was based on flawed interpretation of US Military experiments in which subjects dressed in arctic survival suits (without hats) were exposed to cold temperatures. Since their heads were the only part of their bodies left uncovered, scientists wrongfully assumed that the head was the source of the majority of heat loss when, in fact, heat loss can occur through a variety of thermoregulatory mechanisms – conduction, convection, radiation. If the myth were true, they say, humans would be just as cold if they went without a hat as if they went without pants. The actual amount of heat loss depends roughly on the body surface area that is exposed.
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Tags: army, cold, conduction, convection, hat, head, heat, military, myth, radiation
Dr. Steven Chang, the author of DailyDose, is a staff physician with Kosmix RightHealth. Dr. Chang practices Family Medicine at the University of California Davis Medical Center, where his medical interests include both pediatric and geriatric care, public health, gay and lesbian health, and sleep medicine. Dr. Chang trained at the Stanford University affiliated O'Connor Hospital, and was a research fellow at the National Institute of Health. He holds an M.D. from McGill University and a BA in Public Health from Johns Hopkins University.
December 19th, 2008 at 6:48 am
I think the 1970 study was misunderstood… And who gets paid to run these debunking experiments anyway??? I want a job at the Indiana University. I think the 1970 study was trying to explain that your major heat loss, when in cold temperatures, is your face and head. They assumed that the rest of your body is covered up because typically if you are in a cold enough environment that would warrant even considering wearing a hat, the rest of your body is covered up. So, if you are in a cold environment without a hat on 45% of your heat loss (at that time) is coming from your head. “Flawed interpretation” is wrong. Here’s a question for you; if one end of an iron rod is heated and then the rod is placed out in the cold where is the most “heat loss” coming from the rod? If a naked body is out in the cold, where is the most “heat loss” coming from? Of course the head is not 45%! It is one of the “hot spots” though.
December 19th, 2008 at 10:59 am
Idisagree with the study. I am cold most of the time and wear a hat and sometimes a scarf over my hat. If I get too hot, I remove the scarf and then my hat. but usually my hat is on all dayand night. It does not matter if I wear 4 sweaters, wrap a blanket around me, wear gloves or wear extra socks,if my hat is not on I am cold. Another point, I just discovered, wearing a scarf or covering the back and front of your neck will also keep you warm. Lastly, there may be some truth about heat exiting from the face. A few nights ago, I was lying in bed and my face felt extremely cold. At that moment, I wanted one of those ski masks, where everything is covered except the nasal area and eyes. The next time one is on sale, I am getting it. Thank you.
December 19th, 2008 at 2:13 pm
looking solely at the maths, physics and logic, then perhaps yes, the indications are that hats are not the be all and end all of keeping warm; but the complexity of the human mind and body and its individuality is not something that can be determined with a calculator.
December 19th, 2008 at 5:45 pm
I disagree also with the study. I am cold a lot of the time & when I bundle up except for my head I am still cold. If I put a hat on I start to warm up fairly quickly & as soon as I take the hat off but leave every thing else on I get cooler fast & soon get cold again & need to put the hat back on.