I do Brazilian Jiu Jitsu and a common submission technique is to cut off blood flow to the brain (known as a blood choke). I've lost consciousness twice after being put into a blood choke. The experience of regaining consciousness is visceral. For those that haven't experienced it, it's very much like a turning on a computer. Initially, your brain does not (or cannot) process input like vision, sound, touch, etc. Slo…
The way I understand it as the blood pressure drops your brain stops to function properly but it might still somewhat function. As blood pressure goes back up more parts of the brain resume normal function but the "functional" state of the brain might still be abnormal. The current state is unstable, especially when new functionality starts to come back online and resume normal behavior, and the state of the brain quickly moves from a unstable state to a more stable normal state.