Almost all college students suffer from this. Try playing some outdoor sports or heavy workout in the gym after you are done with your homework and assignments in the late evening.
I assume your school is up to 2PM or at max 4PM. Come home, do lunch finish your homework or any extra study you need to do. Go outside at 6, and commit to a heavy workout or some outdoor sport. Come back in at 8 or 9. Do everything you have like dinner/video games or entertainment during this time.
By the time you hit bed at 12 you will be so tired you will sleep like a log. If you hit the bed and not sleeping, either you did not tire your body enough or you have insomnia.
You don't have to follow the exact schedule you can switch around things ofc but try to tire yourself. Maybe you are on your phone during the night? That effects sleep a lot. In that case try to shift all activities on digital devices early in the day. However, sitting at home and doing nothing barely puts any strain on your body and your body does not feel like sleeping.
Anyways best of luck and don't hesitate to ask any doctors for help regarding this matter. What I mentioned above is just something I do when my sleep schedule effects my acads too much. I am not a huge gym person so I personally play badminton for outdoor sports.