What do I do!? HELP!

Ok, so my bf and I live downstairs from his sister. We are all very close. I have only 1 issue, yep you guessed it, the noise. She has 4 kids, her and her bf. I honestly am a bit jealous, i dont know how they do it. They are up very late and very very early. The noise is almost constant. Its either the kids running, them walking, or their surround sound system. Dont get me wrong, i like a loud movie as much as the next person, but at midnight when im trying to get my older daughter who is sick to sleep, not so much.. They know they make noise because they have had me tell their kids that theyre making too much noise (not that it works). Anywho, what can i say or do without sounding like a crazy person? At this point i feel crazy about it.. Please any info needed!