I want a brutaly true answer. My first one a year ago was a severe one. I was playing rugby and someone smashed my head on the ground (I was knocked out) I don’t know how long but people around me said my eyes went to the back of my head. Plus I couldn’t remember anything past that. I woke up at school infirmary and failed the concussion test, couldn’t even distinguish a chair from a table. He most recent one I also lost consciousness, I passed test this time.