I love hot showers, they relax my computer neck muscles and I assumed improved blood flow. I've heard cooling the body can be beneficial in some brain injury but the temperature has to be dangerously low. I guess just use common sense regarding temperature.

PCS can cause autonomic disturbances so body temperature regulation, pulse rate and breathing can be affected. This is controlled mainly by the brainstem so a whiplash type injury could do this. For many months I had a problem with overheating while sleeping, I'd wake drenched in sweat, and even now my pulse has only just gone back to where it was before my injury.