Teen daughter waking up at night

this is an issue I have never had so I need some ideas :) my 15-year-old daughter wakes up all night long and the problem is when she doesn’t get enough sleep at triggers a migraine and then she misses school the whole next day. She is not an anxious kid, and her phone is off all night. What can I do to help her sleep and stay asleep?

She already takes magnesium and is otherwise healthy, and active.