[petke]

That makes it sounds rarer and worse than it is. I think its more a choice than a medical disorder.

Its quite normal. If you work at home and have no family or other obligations that keeps you in sync, you tend to sleep in a bit longer than strictly necessary simply because you can. Naturally you go to bed later also. Now your day has become more than 24 hours. If you are allowed to do this every day, you get very out of sync with the rest of the world and occasionally line up with it again.

[LifeQuestioner]

I assure you, a circadium rhythm disorder is not a choice.

For some staying up late is a choice, it may be environmentally caused but for those with a disorder it's not. It's a problem from birth. I'm speaking more about delayed sleep phase syndrome though, I dont know much about non-24.