You can definitely overheat yourself in a bath, unlike a shower. I use the thermometer so I don't really have to attend to things like sweating and the like. Baths, and hot tubs, can really be deceptive because you feel so good most of the time. People have gotten sick, even died. 104 degrees (F) is the critical danger point.

I just read a paper that found that mild TBI brains are actually COOLER than average, believed due to reduced metabolism. But I just wondered how high should I go, like 99.6 was the limit I've been using.

It's also well known that mTBI brains don't metabolize glucose as effectively. Perhaps this is why it's better to eat round the clock. Maybe mTBI people should have their glucose uptake measured, it could help pinpoint where they are in recovery etc.