I became a night owl after retirement, when I no longer had to get up at 6:00am.
I have severe tinnitus which is much worse when it's quiet & I need the TV on at low volume for 30 minutes before I can fall asleep.
And, with diabetes, my blood sugar will swing up & down while I'm sleeping, which causes symptoms that can make falling asleep impossible. Sometimes it will get too low, which causes a rapid, pounding heart & shortness of breath. Then I have to eat sugar & it can take most of the night to feel normal.....or it will then get too high & cause the same symptoms.
A few times per month, I'll be up all night & just sleep a little earlier the next night. I'll read a book, play my piano, or (if it's not too cold) go outside where I feed 4 raccoons. They're fun to watch.