Instead, I recommend looking at a schedule with your student. Where can you fit in practice time, homework time, or rehearsal time that doesn't take away from sleep? Can you fit in five or ten minutes of practice before school. Or can you put away the Pokemon Go for ten minutes in the afternoon to work on homework. Write down what your student does all day - minute by minute from the moment they get up until they go to bed. Help them set a schedule and then encourage them to stick with it. Did they commit to ten minutes of practice as soon as they get home from school? Remind them when the television comes on first thing next week.
Making a schedule and then committing to the schedule is the hardest part. Have your student sign the bottom and then give them gentle reminders when you see them forgetting the agreement. In a matter of a few weeks, you'll notice the schedule becomes the norm - homework, practicing, sports, rehearsals, and most importantly - sleep - will all seem to happen effortlessly.