"I don't dream since the brain injury."
I used to think that, but then a daughter told me I was making noises in my sleep. She said I was barking!
I really was probably dreaming about a dog.
You can tell if you are dreaming with this trick. It's not 100%, but it can give you an idea. While you are asleep, someone needs to look at you. They shouldn't stare. I can't sleep if someone is staring at me.
If they can tell your eyeballs are moving under your eyelids, then there is a good chance you are dreaming. REM or rapid eye movement is the stage of sleep in which we dream. This isn't fool-proof, and the other person might not be able to tell.
You really are dreaming. You just don't remember any of it. Memory issues can be a problem of brain injury. If you don't have memory issues or a brain injury, you are NOT dreaming, and it bothers you, seek further advice. Remembering your dreams ranks pretty low on a list of needs. I just went without. Some people go without dreams their entire life and do just fine. To me, remembering your dreams is a luxury.