The impact of a concussion affects the mechanical, physical, and biochemical functions of humans, their organs and the cells of which they are composed. These processes can be interrupted or over stimulated with brain injuries changing how the organs function and or control processes in the body.
After a head injury the brain experiences decreased blood flow and a disruption in autonomic regulation. This leads to a higher likelihood of transitioning to a fight or flight state, during physical or mental situations that are usually easily managed. this may prsent itself as a short temper, irritability, anxiety, fatigue, frustration and exhaustion.