Hmmm yeah I've thought on that before. But often I'm told you can't have both, you either have one or the other. Which kinda makes me think "then why can you have some that dont while many other can coexist with eachother?"
Just like Borderline Personality Disorder, Bipolar, Add/Adhd, sleep deprivation, can't really be coexisiting diagnoses (though Sleep Dep has arguments on both sides. I personally believe it can. Just like i am ADD/ADHD, but when i get sleep deprivied it worsen's it to the max!