Can i get an easy to understand explanation of concussions please.?

Impaired function: Concussion occurs after some trauma to the brain. It can affect your physical state, thinking ability, emotional state, and can affect your sleeping pattern. Some common findings are headaches, nausea, sensitivity to light and noise, fatigue, visual problems, problems concentrating, emotional irritability, drowsiness, sleeping problems. There are tests that can be performed to gauge the severity.