Does anybody have advice on sleep insomnia? Please help!

Devyn • Seventeen
I used to be able to fall asleep in minutes, but lately I've been stressed and find myself trying to force myself to sleep and not even going to bed until 12:30 to 1a.m. I also wake up for school at 6:40 a.m. so I'm always extremely tired and not focused, it's affecting my grades. Please help!