One common issue after a serious brain injury is known as sensory flooding. It can make it all but impossible for the injured person to hold a job or go out in public.
In an uninjured brain, all of the sensory input gets filtered and sorted through very quickly. Your brain learns what is important and what you need to focus on. It cuts back on the "noise" and allows you to pick out important details.
After the injury, those filters may stop working properly, and then your brain has no way to sort through all of the sights, sounds, lights, smells and other types of input. It's sensory overload. You can't concentrate and you feel overwhelmed.
This is why people who have brain injuries often need time alone in a dark, quiet room. It's not that they don't want to be social or that they do not like interaction with their peers. They just need some time without so much input so that they can rest and give their brain a break. They don't have the filters that everyone else takes for granted.
In some cases, however, the overloading can also come from your own thoughts. You may feel like you cannot "turn your brain off." You can't stop thinking and calm down. You have trouble sleeping. Your thoughts consume you and you can't focus on anything else. You may get fixated on certain thoughts that you just cannot shake, no matter how unimportant they actually are.
Many outsiders do not understand how a brain injury affects you or how drastic the ramifications can be. Make sure that you know how to seek compensation and explain your symptoms accurately.