Major sleeping problem

Patient: Hi, 2 or 3 years ago, i worked on a nightshift 5 days a week. I worked for like 3 months, but since then, i can`t go to sleep early, i just dont want to sleep till about 4 am. I oversleep class almost everyday and even when i wake up at 11-12 am (after 7-8, sometimes even more) hours of sleep, i still feel sleepy and tired for the whole day, even coffee or energy drinks dont work. I start to feel better at about 10 pm or so. How can i fix this? Few times i managed to fall asleep at 10 pm and wake up at about 7, i felt great the whole day, but then again, i couldnt fall asleep that day till about 3-4 am, i was laying in my bed with my eyes closed for 2 hours and i still couldnt sleep.

Symptoms: Not being able to go to sleep