Witching hour

For the past couple of months my 6 month old has been waking up at 3 am for her feeding this has never really been an issue until recently when she decided that sometimes she'd rather stay up for an hour and play rather than go straight back to sleep. I don't really like leaving her like that, we have a music player on her crib that lights up as well as a night light but she doesn't seem to pay much attention to them that late. I'm just wondering if anyone has an idea why this is happening and if there's a way to end it?