For me, the "night owl" manifests as clarity of mind. My mind feels clearer as the day progresses and clearest during the evenings. If I try waking up at 6:00 AM or something early like that, I'm foggy all day until ~10 PM when I should be getting to sleep, then I'm exhausted with a clarity I hadn't had all day so I don't even want to sleep, I want to do something.

It's like, when the sun is down, my brain is ready to be super productive.