I just want to sleep!

Liz • 21. Student. In love.
Last month I was taken off birthcontrol. For the past two week (or so) I have been exhausted during the day but once I lay down to go to sleep I am wide awake for at least 4 hours.
Do any of you ladies have any tips or tricks for falling asleep? I'm exhausted but even when I take melatonin I still can't sleep. Thanks!!