There has been discussion about the Embre watch thing which I think is about 95% BS. Just too small to do much of anything and it only works after it is too late.
Early on on the web site of the mfg there was mention of an article (now gone) about social thermo regulation. This was just about the only bit of information that suggested why the device might work but again, it is just too small to do anything.
However this is not the case with a large dog. The article discusses the tendency of social animals to achieve the same body temperature when in close proximity, this being social thermo regulation.
After traveling to Europe with my service dog, he has become more attached to me and allows me to sleep in contact with him for a longer time than he would before. If I am in close contact with his warm body, I never have a hot flash. My other Poodle is more compliant so maybe she will have to be the regulator.