Sleeping problems

For the past few years I have been sleeping at 6-7 am and waking up at 3 pm..

Is this called insomnia??? Whenever I have to get up early I don't seem to go back early in bed😟

Is there a way I could get on a regular time schedule?

PS.I am a student and I have always been to afternoon school when I started college which resulted in studying at nights.

Now I have finished college ,and studying management which is In the afternoon but I want to study in the mornings now and change my sleeping schedule.. But It just can't happen. I do not feel like a human being at all.. :( what should I do?