I have no idea how to stay sane over the next 5 days...

My cousin invited me on vacation with her parents husband and kid, and I know i should be grateful because I don't really have to pay for anything, but im so stressed out. I've been up since 8 am and barely got to sleep at 1 am. I woke up at 5 because my niece got up again. My niece 4F basicly decides if she wants to sleep with her parents or grandparents and I'm on a bed next to her grandparents (my aunt and uncle). Haven't been asked to help put her down at all, but I feel bad watching my aunt having to deal with it. How do I survive the next 5 days??