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/
I was diagnosed with DSPOD about a year before I was diagnosed with ADHD.
I mention that because I've often heard the statement that "of course people with ADHD have fucked up sleep, they have to take amphetamine to treat it."
I cannot sleep at night without medication. With or without adderall, I can sleep from about 5am to noon if I didn't sleep the previous night.
It's only recently I've become comfortable with the term of nuerodivergent, but the truth is, my brain appears to function slightly different from nuerotypicals.
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