My 10 year old sister stays awake until 4am every night. What can I do?

I am 21 years old and temporarily living with my dad.Almost 6 months ago, my 10 year old sister started refusing to go to my moms house. (My parents are split up). My dad lets her have free run of the house. She can eat what she wants, go on the computer all day, and stay up/sleep in until when she wants. There are a whole list of problems but I would say the biggest problem is her sleeping habits.She is on her iPod until 4am most nights. On school days she goes to bed at 4am and gets up at 7:30am. On weekends/holidays she doesn’t get out of bed until after 12pm. She gets absolutely no physical activity as far as i’m aware because she’s always on her iPod or computer. I have tried multiple times to get her to go to sleep earlier but it always ends up with her throwing a tantrum and my dad screaming at me to mind my own business.Is there anything I can do at this point? via /r/Parenting https://ift.tt/2sjabYV