I have never been a late night person. 10pm is late for me. I was always the child who willingly went to bed early. Maybe because I used to ice skate for a couple of hours before school that helped me with going to bed. But I have never lost the habit. When I met my husband I was pleasantly surprised that he is on the same schedule.
Our cat is the 5am kitty. For some reason he has decided its his breakfast time. We do not really appreciate that part. He has a little internal alarm clock that is consistent every day, including weekends. (When he visits my parents when we are away, they say he doesn't bother them until much later.)
I am a morning person as well. I have also had the problem of waking up at 3 am regularly and usually get back to sleep with in a reasonable amount of time. Sometimes I am up for a few hours. Then I would get up in the morning a little cranky but okay.
But last spring I changed some of my prescriptions and one of them makes me tired. I'm not sure which one for sure but I think I can narrow it down. Anyway, I don't feel as tired in the evening and go to bed at my normal time. But I can't wake up in the morning.
Today was no different. I went to bed at my normal time last night. Woke up at 230 and was up for a bit. Then I slept through the alarm and three snooze alarms. Finally I woke up and realized 'crap, now I'm late'. But at least I got my 8 hours in.