does anyone have any good remedies for getting to sleep???? i have had MAJOR problems getting to sleep lately and i dont know why

it is now 330 am and i had gone to bed at midnight........ i was more or less just waiting to FINALLY fall asleep but it isnt coming, i dont know whats wrong with me

school is starting soon and this can not be a regular habit anymore, i could kind of deal with it because i was on vacation but now that i am going back insomnia isnt going to work!