For me, 6 hours sleep a day during the week, 10-12 on the weekends. Of course, I normally get one or two days with 2-3 hours and on friday, it's not too uncommon for me to be up 24+ hours.
Now my english teacher, she's fvcking insane; she's up till 2-3 everyday and then has to get up around 5:30 to get to school early. We all know this becasue we email her at 2am with questions on papers and she's like, yeah, I admit it, I'm lucky when I get 4 hours of sleep.