# Body heat loss through head **URL:** \ **Category:** Factual Questions\ **Created:** [October 19, 2005, 7:19pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960 "2005-10-19T19:19:07Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![The\_Davil](https://avatars.discourse-cdn.com/v4/letter/t/cab0a1/32.png) [@The\_Davil](https://boards.straightdope.com/u/The_Davil)\ **Post date:** [October 19, 2005, 7:19pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/1 "2005-10-19T19:19:07Z")
OK, we’ve always heard that you should always wear some sort of head covering when it’s cold out since “50% of our body heat lost is through our head”. I remember hearing somewhere that the study that originally provided the 50% number was an old (1950s era) military study that was based on erroneous data, and that the real number was nowhere near that. A Google search turns up many absolute citations of 30%, 40% and 50%, and this one: [http://www.msu.edu/user/manns/myths.html](http://www.msu.edu/user/manns/myths.html) (myth #18) seems to at least partially confirm the “50% is BS” theory. None of these sites, however, cite any sort of actual study, just a blind allegiance to whichever number they picked out of the sky. So anyhoo, does anyone know of a study done by a reputable source, and if so, can you provide a citation? Don’t know why this is bugging me so much, but I read someone in a scuba newsgroup toeing the “50% heat loss” party line and I’d like to know for sure. Or as sure as I can get… Any help? Thanks, David ---
**Author:** ![lissener](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lissener/32/6139_2.png) [@lissener](https://boards.straightdope.com/u/lissener)\ **Post date:** [October 19, 2005, 7:21pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/2 "2005-10-19T19:21:53Z")
No scientific answer here, but anecdotally, I stopped being miserable waiting for buses in the Chicago winter when I learned to wear a hat. It seems to have the effect (for me) of just making me feel warmer in general, and not just the top of my head. ---
**Author:** ![AskNott](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/asknott/32/5790_2.png) [@AskNott](https://boards.straightdope.com/u/AskNott)\ **Post date:** [October 19, 2005, 9:49pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/3 "2005-10-19T21:49:05Z")
I remember reading that the “If your feet are cold, put on a hat” theorem was being challenged by somebody. The original idea was that not only a lot of heat was radiated by your bare head, but that the body’s “thermostat” was located in the back of the head and neck. While there may be contrary information out there somewhere, I continue to put on a hat when my enormous feet are cold. I hate having cold ears. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 19, 2005, 10:00pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/4 "2005-10-19T22:00:39Z")
Again, no scientific answer here, but worth considering is that the head, notably including the brain, has a considerable blood supply; in cold conditions, blood vessels in other parts of the body constrict to reduce flow and conserve heat; the brain doesn’t - it keeps on going (the alternative would be loss of consciousness). ---
**Author:** ![wolfstu](https://avatars.discourse-cdn.com/v4/letter/w/d6d6ee/32.png) [@wolfstu](https://boards.straightdope.com/u/wolfstu)\ **Post date:** [October 19, 2005, 10:16pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/5 "2005-10-19T22:16:36Z")
> [@Mangetout](#): > > Again, no scientific answer here, but worth considering is that the head, notably including the brain, has a considerable blood supply; in cold conditions, blood vessels in other parts of the body constrict to reduce flow and conserve heat; the brain doesn’t - it keeps on going (the alternative would be loss of consciousness). On top of that, the head is also relatively poorly insulated. Between the brain and the atmosphere, there’s a few membranes and a thin layer of bone and skin, but no thick layer of fat or significant muscle like on the rest of the body. Fortunately, there’s a lot of hair, but many people have cut most of it away (or it’s fallen out due to age). Short hair isn’t a great insulator when it’s windy, and if hair gets wet it’ll act as a big heat sink, thieving energy from your head. I don’t know about numbers, though. ---
**Author:** ![Jake](https://avatars.discourse-cdn.com/v4/letter/j/f475e1/32.png) [@Jake](https://boards.straightdope.com/u/Jake)\ **Post date:** [October 19, 2005, 10:26pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/6 "2005-10-19T22:26:36Z")
When I first saw the post I read “Body Fluid Loss through Head.” Sorry. 😉 ---
**Author:** ![drhess](https://avatars.discourse-cdn.com/v4/letter/d/94ad74/32.png) [@drhess](https://boards.straightdope.com/u/drhess)\ **Post date:** [October 19, 2005, 10:34pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/7 "2005-10-19T22:34:21Z")
Save energy…decapitate yourself. ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [October 19, 2005, 10:39pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/8 "2005-10-19T22:39:44Z")
> [@](#): > > **[Brain temperature, body core temperature, and intracranial pressure in acute cerebral damage](http://scholar.google.com/scholar?hl=en&lr=&c2coff=1&q=%22Brain+temperature%2C+body+core+temperature%2C+and+intracranial+pressure+in+acute+cerebral+damage%22&btnG=Search)** > (mine bolded) > The brain is a big consumer of energy and a big producer of heat, **which is not easily dispersed because of the insulation provided by the skull**. The brain uses about 20% of the oxygen and 25% of the glucose required by the body at rest (when it weighs only 2%-3% of the total body weight) […] In our population a consistent difference was found between cerebral temperature and internal body temperature, confirming previous reports. In most patients brain temperature was higher than body core temperature. The differences measured were quite large […] > [@](#): > > **[The human thermal plume](http://scholar.google.com/scholar?hl=en&lr=&c2coff=1&q=cache:2W8OXPaY7Q0J:www.me.psu.edu/psgdl/PortalCBW.pdf+%22body+heat%22+%22top+of+the+head%22)** > Human skin, typically at 33°C under normal activity levels, is about 9°C warmer than the surrounding air at room temperature. This causes a steady thermal convection process that transfers heat from the body to the surrounding atmosphere. Such convection conveys waste body heat at a rate of 80-100 W for a resting person, thereby helping to maintain a healthy bodily thermal equilibrium. The air heated by the skin rises naturally according to Archimedes’ Principle, generating a free-convection boundary layer about the body and a thermal plume above it […] > > The convective boundary layer of a person standing still in quiet air begins at the ankles and travels up the legs and torso, growing thicker and faster as it moves […] For a standing nude man 1.7 m in height, the boundary layer is laminar until about 1 m above floor level, and is fully turbulent above 1.5 m (mid-chest height) . This natural boundary layer grows to approximately 15 - 20 cm thick around the head, where the maximum upward airspeed is in the range of ¼ m/sec. This upward flow separates from the shoulders and the top of the head, as the body surface becomes horizontal. The resulting human thermal plume continues to rise above the body itself, where it reaches a typical overall flow rate between 50 and 80 liters/sec . The plume extends for a few meters above the head, headroom permitting, before it dissipates due to turbulent This natural human convective airflow pattern is similar for everyone despite differences in body height, weight, clothing, etc. > [@](#): > > **[Regulation of cerebral blood flow](http://www.thedoctorslounge.net/studlounge/articles/cerebcirc/cerebcirc4.htm)** > Cerebral blood flow (CBF) in man is about 50 ml / 100 g of brain / minute. […] Preliminary conclusion: Your brain is a haemodynamic monster and it is chewing up a proportionally gigantic amount of your bodies resources. That said, (and on preview, contrary to **wolfstu** ’s post), your skin, galea aponurotica, bone, epidural space, superior sagittal sinus, dura matter, subdural space, arachnoid, subarachnoid space, and pia mater actually provide pretty good insulation (those come not from my brain but a post of “The Brain” on my wall showing everything that comes between cortex and air). Not sure what to say about the “human thermal plume,” but intuitively, heat rises, and if the plume is going upwards it makes sense that it’s going to take some from the top of your head with it. _dons beanie for good measure_ (this _is_ colorado!) ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [October 19, 2005, 11:20pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/9 "2005-10-19T23:20:15Z")
> [@alterego](#): > > heat rises Silly nitpick: _hot air_ rises, not exactly the same as heat ---
**Author:** ![ticker](https://avatars.discourse-cdn.com/v4/letter/t/d07c76/32.png) [@ticker](https://boards.straightdope.com/u/ticker)\ **Post date:** [October 19, 2005, 11:34pm UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/10 "2005-10-19T23:34:08Z")
Surely the % will depend on how well insulated the rest of your body is, otherwise the 50% claim would imply that you would be just as warm standing at the bus stop naked except for a fur lined hat as you would be well clothed but bare headed, which sounds absurd to me. That being the case all quoted % figures are questionable as they all make assumptions about your other clothing. ---
**Author:** ![1010011010](https://avatars.discourse-cdn.com/v4/letter/1/ea666f/32.png) [@1010011010](https://boards.straightdope.com/u/1010011010)\ **Post date:** [October 20, 2005, 1:29am UTC](https://boards.straightdope.com/t/body-heat-loss-through-head/326960/11 "2005-10-20T01:29:51Z")
The rate of heat transfer between two substance is determined by the difference in temperature between them. So all else being equal, a warmer body loses heat faster than a cooler body. Surprisingly, there doesn’t seem to be a lot of thermal imaging porn on the internet yet. I mean, they have midget clown porn, but no infrared nudie pics? How am I supposed to… ah… do research? As for the “Completely naked except for a furry hat!” comment… you’d be surprised.