This post https://backofthebookshelf.tumblr.com/post/160338761264/what-are-the-symptoms-of-adhd-besides discusses a few ways that ADHD can manifest that I've not seen mentioned elsewhere.
The specific part of interest for me is (paraphrased) when one learns to internally fulfill the need to Constantly Do Something Stimulating.
That is a very feasible explanation for all the noise and feelings and spaceiness in this brain.