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Comment by easytiger | Hacker News Reader

It might be worth the author noting that the reason this works is that the area that it's placed at the base of the neck changes perceived thermal strain. it is an ancient trick that when one holds an ice cube there it makes you feel temporarily cooler. The brain gets false information as to the surface temperature and makes slightly different cooling decisions.

So your body can get to higher temperatures whilst you have a longer period of tolerance of it. There is some question as to the safety of this for people who might not be of athletic ability etc. It likely will allow increased, often significantly, blood pressure. In older people this could be dangerous if that is the case.

https://link.springer.com/article/10.1007/s10072-020-04349-x https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3017491/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5968886/

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>So your body can get to higher temperatures whilst you have a longer period of tolerance of it. There is some question as to the safety of this for people who might not be of athletic ability etc. It likely will allow increased, often significantly, blood pressure.

Is it possible to use this effect to get the opposite result? that is, fooling the brain to perceive itself to be hotter than it is to overcharge the cooling mecanisms at the cost of an unpleasant feeling of heat?

Wouldn't you simply put a warm object on the neck instead of a cool object?

Yes that's often given as a possible explanation for the popularity of hot drinks and hot spices in warmer climates.

https://www.npr.org/sections/thesalt/2012/07/11/156378713/co...

Yes, there is a bracelet that does both heating and cooling effects:

https://embrlabs.com/

Maybe it's a placebo but I wash my hands with cold water in the summer and I believe it makes a small, but noticeable, difference in cooling me.

It does seem like shoes are a better place for this technology -- the feet see a huge amount of bloodflow, and shoes tend to trap heat so there's a bigger thermal differential to exploit.

Because the only way for one side of the device to be cooler is for the other side to be hotter, this particular device must be positioned where the heat from the hot side will dissipate away from the person. (Apparently, heat dissipates fairly well through the kind of shirts people wear in hot weather.) So, putting this particular device in a shoe would not cool down the foot because shoes don't dissipate heat well.

What would cool down the foot would be a device consisting of 2 parts connected by a hose, which would carry liquid from the part in the shoe to the other part (which could be strapped to the bottom of the leg). The liquid would carry heat away from the part in the shoe. A second hose would be needed to return the liquid to the part in the shoe. Call the part outside the shoe the radiator.

Oh god no, don't seal them in the shoes! The device would require custom shoes with venting to dump heat out of the top of the toebox. Or as you say, an external leg-mounted heatpump, but that sounds quite uncomfortable

>The device would require custom shoes with venting to dump heat out of the top of the toebox. Or as you say, an external leg-mounted heatpump

Sounds like a job for Sietch Tabr!

There is already a device like this which uses the wrist: https://embrlabs.com/

I seriously doubt the author was aware of that.

Regarding the ice cube technique, I found some freezable bandanas on Amazon that have the same effect as holding an ice cube or using this Sony device.

Interesting.

Are the dangers still significant for shorter durations? For example, a 10 minute subway journey.

My first thought was “this would be useful for mountain biking in the desert”. But if much of the effect is perception, it seems like it could be very dangerous in an athletic situation.

I don't think the dangers are significant at all. The danger would come from changing how you perceive your level of heat, causing overheating related issues to come without you noticing the warning signs. If you ride the subway for a 10 minute commute every day, and it's a little warm, you will have virtually no side effects from this.

There aren't new side effects, there is just a hiding of symptoms.

would it be safe to wear this while exercising heavily?

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