The messed up sleep cycle is likely their own doing, but delayed circadian rhythm has been connected to ADHD. The main debate has been whether one contributes to the development of the other, but it's most likely they go hand-in-hand.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6487490/
Anyone regularly up that late does have a higher chance of being some type of divergent, but lifelong suffering is not a requirement to make people create. Anyone can do that. The whole correlation/causation thing
I mean I've written all my poems and "songs" at 3am because that's usually when the alcohol induced depression hits hardest and I need to put that energy somewhere or I'm gonna do something really stupid
Accurate. Really fucks me up when I have morning meetings. I become really incoherent. Luckily I work as an art director and everyone expects me to speak incoherently about design anyway.