system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Is there a physiological explanation for 'seeing red' during a fight? I don't mean being knocked unconscious, more like battle rage.
gpt
When you are in a rage, your body releases tons of adrenaline.  Adrenaline is a hormone which prepares your body to "fight or flight".  This redirects blood flow away from processes which are "non-essential", and to other areas which can help you run or fight.  This means a lot more of your blood is going to your muscles, and less of it is going to your brain.  Potentially, this can cause your brain to be short of oxygen, which could impair your ability to see straight, the same as when you are about to pass out.  This can cause your vision to fade to red or black, or give you tunnel vision.