Need motivation/tips to go sleep earlier

[Gonken]

So yeah, school's starting in a few weeks and I can remember from the last year that I stayed up very long each school day and only had around 5-7 hours of sleep per day. Which makes me very tired in the mornings which keeps me tired the first hours of the school day. I need tips on how I can get to sleep earlier so I can sleep better and not be so tired during the start of the day. I am aiming for 8+ hours of sleep per day. I sleep 8-10 hours during weekends (I try to keep it below 10). My main problem is, I don't go to sleep because I ain't tired. I get tired too late which results in this small amount of sleep. Note: "Just go to sleep earlier" doesn't work for me, because I ain't tired and it usually takes me 30min to 2 hours to fall asleep if i go to bed earlier.