For university, I have irregular waking hours, but usually between 4:30am and 8 am.
I usually go to sleep sometime between 11:30pm and 1:30am. I have only about 4-8 hours of sleep, more often about 5 hours.
I sometimes take naps when I get home from uni, but its not intended. It's like I collapse from exhaustion and a bad sleeping routine - if you can call it that...
Holidays, I sleep until about 7am and go to sleep at about 11ish.