How to catch up on sleep?

urgh. i look dreadfull. i have MASSIVE bags under my eyes and they look awful-_- i need to catch up on sleep but when do i do it? because im at school monday-friday i go to sleep at 11-11:30 and wake up at 7:50 on friday night i stay up and watch stuff on iplayer and same on saturday going to sleep at like 2ish to 3ish in the morning and waking up at 11-12 or sometimes 1-2pm... and then on sunday night (tonigght) i can never get to sleep cus i woke up late so i go to sleep at like midnight:L how can i catch up on sleep?:)