I know this is a bit off topic, but I`ll join in.
My normal body temperature is 37.8C. I don`t consider it a real fever until I am hitting 39, and will shoot up to 41 quite easily. I`ve been hospitalized for a fever of 42, and lost hearing partly in one ear because of it... (I only notice it when I`m listening to something on headphones as I will need to turn one side louder than the other for it to sound even.) Our policy now is a cold shower and trip to the hospital if it goes over 41.5 after taking fever medication.
My mother in law was nearly in shock when I was ill with a fever of 39, but still fine and able to be up cooking dinner. My husband is about 36.4 average, and my son jumps around so much I really can`t even guess what his average is. I have seen them both in the 35 something range. (I think I`d die if I dropped that low... I`ve never been below 36.5, and that was only once - I was so cold that I couldn`t stop shuddering.) Both of them are literally collapsing at anything over 37.5.
Japanese people do have a lower average body temperature, but it is my understanding that it is only 0.2C less than the average European. Most people I know average about 36.8C (Yes, I ask...) I don`t really think this would have a huge effect on the impact of heat on the body.
I think it really comes down to the individual and not their core temperature. I am happy with my high base temperature as I seem to get sick less and get quick high fevers that kill everything off, so I get better very quickly.
My temperature is quite high, but I am still fairly fine in the heat of summer - and don`t even really sweat all that much so must be doing alright at regulating my temperature. I am also quite comfortable in the cold of winter. However, despite my high temperature, I have a mild form of Raynaud's phenomenon which can make winter a bit of a pain. People find this stunning as they always assume it is linked to a low body temperature because doctors lump it in with 冷え性 - something anyone who gets cold and shivers loves to complain and say they have.
