I feel really sleepy , i can't sleep much at night only after 5.am and i wake up at 11,12 in afternoon so i get about 7 hours asleep,is it not enough?

That's fine if...: If a person works the 3 - 11 p.m. shift, and then does other things until about 5 a.m., it's fine to sleep 5 a.m. to noon. Otherwise, there may be a problem... one that a trip to the primary care doctor can help figure out. It is hard to make a person fall asleep. So, to reset a sleep schedule, it is easier to set the WAKE-UP time earlier each day until the desired proper WAKE-UP time is reached.