FEELING cool vs. BEING cool

Factual Questions
1

This question is about human body function, not attitude.

This past summer, on a very hot day I was performing strenuous physical activity, and my body temperature increased. My body automatically responded to cool itself, including (but not necessarily limited to) vasodilation and sweating. Even so, I was uncomfortable. I “felt” hot. I assume this feeling was one of the autonomous responses designed to cool my body (i.e. my brain was telling me “you’re uncomfortably hot, you want to go somewhere cooler, like shade, and stop exerting yourself”).

Fortunately, I had a cooler containing ice and a large bottle of water. In addition to drinking the water, I was taking this large, cold object (the bottle) and placing it on the back of my neck. Almost instantly I “felt” cooler. When I took it off my neck, within several seconds I “felt” uncomfortably hot again.

Someone told me this was because the ice cold water bottle was cooling the blood reaching my brain, and thus my brain was “tricked” into thinking my whole body was nice and cool. So instead of “feeling” hot, I “felt” nice and cool, even though I wasn’t.

(1) Is that roughly an accurate explanation? Roughly, approximately, close enough?

(2) If so, here’s the real question. Is it possible to “trick” the brain into thinking the body was cool enough, so much so that it shut down the other autonomous cooling responses like vasodilation and sweating? And if so… could this scenario be dangerous? By “tricking” the brain into thinking it is cool (enough) so it shuts down the other cooling responses, when in fact the body really is too hot and really does need those cooling responses?

(I guess this would be literally analogous to a car engine with a faulty thermostat. If the thermostat is malfunctioning and reading way too cold, the engine might overheat because the cooling system (coolant pump) wasn’t activated.)

Many thanks.

2

Your brain doesn’t have any nerve endings. It doesn’t know how hot it is. Your brain just gets information from everywhere else. I suppose when your brain itself overheats you just pass out, and in extreme cases get brain damage.

There may be some other type of trick going on there, though, similar to getting a brain freeze (a misnomer, of course) when you eat or drink too much of something cold.

I don’t know much about anatomy so anything else I would say would be speculation, but I will speculate that your body’s heating and cooling controls don’t have anything to do with your subjective perception of whether you’re hot or cold.

3

Cold on any area cools the blood flow in that area, and it is a calming and relaxing experience in heat, which also promotes cooling and easing of the pulse.

4

Human thermoregulatory set point neurons are located in the hypothalamus.

Thermoregulation

Hypothalamus

Neuronal basis of Hammel’s model for set-point thermoregulation

5

But the hypothalamus is not detecting temperature of the brain using nerves in the brain. Rather, it is receiving signals from the rest of the body that indicate how hot the rest of the body is.

To address the OP: the brain produces a lot of heat, and is one of the more sensitive organs to overheating. As a result, the body will work pretty hard to keep it cool. I suspect the bottle trick does work by cooling the skin and blood flow around the head, it just isn’t the brain itself that’s picking up the difference.

And the hypothalamus isn’t really being tricked - the cold water bottle is cooling you down and the hypothalamus knows it can conserve water/sweat by slowing down your response to heat. When you remove the bottle, it notices the difference and steps back up.

Squink’s links do describe situations in which the hypothalamus can be damaged, producing a faulty response to temperature regulation.

6

I don’t think it’s possible to ‘fool the brain’ with exterior hot/cold stimuli. Our thermoregulatory system is very fine-tuned.

I’ve only ever heard of temp-related deaths from overexertion, fever, and hypothermia - which are all combinations of factors…

With brain injuries, the system can malfunction. This happened to my dad and he would have unpredictable times when he ‘felt’ freezing (along with goosebumps, icy hands and chattering teeth) or overheated (with sweating and hot skin). Nothing external had much effect on these spells of thermo-deregulation. Thankfully they were never serious.

Hormones too can also cause a glitch in the system. Hot flashes, anyone?

7

Thanks everyone.

Isn’t it just cooling the back of my neck, and the localized blood flow? As opposed to, say, jumping in a pool of ice water which would (I assume) cool down the entire body at once?

This is exactly my concern. That one spot in the back of my neck, and maybe localized nearby, is “cool”, but the rest of my body isn’t. The natural cooling systems should be working at full capacity. But by cooling just the back of my neck am I shutting (or slowing) down the natural cooling systems, even though they shouldn’t be? And… is that a problem?

8

I think you bring up an interesting point. I can’t answer for sure, but I can guess you don’t have to worry about it. Here’s why.

People with Multiple Sclerosis are very sensitive to heat. In fact, before MRIs and spinal fluid testing, the clinical diagnostic test was called the “hot bath test”. You literally put a patient who was suspected of having MS into a hot bath, and if their symptoms immediately got worse, it was taken as a confirmation. MS causes damage to nerves and the white brain matter (and, oh, those clever doctors have finally noticed that it causes even more damage to gray matter, which they used to say wasn’t affected by MS at all). This damage is thought to interfere with the electrical whatchamadoogies (sorry if I’m talkin’ over y’all’s heads), impulses, slowing down or blocking the nerves ability to transmit back and forth from brain to body. Kinda like shorts in a lamp cord will cause a light to flicker.

Anyway, getting overheated will usually cause a person with MS to have a psuedoflare, and cooling them off will usually improve their symptoms dramatically. There are items for MSers like cooling vests and cooling neckbands. Wearing one of those or otherwise applying an ice pack or something to the neck or back is pften cooling enough to clear up a pseudoflare. So, cooling only these areas can cool the whole system enough to make the wiring work right again.

Anyway, the point is (now that it’s too late to make a long story short), these cooling vests and such have been marketed for years and years and have been studied extensively. If there was some kind of danger that a cooling neckband would fool you into thinking that your whole body was cool, and there was a possibility your arms and legs would first stop sweating and then get hot enough to hurt you, these devices would be available to patients (at least without extensive warnings).

And, by the way, I had to chuckle. I just saw my neurologist yesterday. He is just the coolest human to ever wear a lab coat. We joke all the time about how little is known about MS and other neurological conditions. He’s often said, “we just know very little about the human brain.” There’s lots of theory, but not much is known for sure about how the brain works.