Can I complain about my upstairs neighbors?

I have complained about stomping and his kids jumping around and yelling and screaming and that, for the most part, has gotten taken care of. My only issue still with this guy is when his kids aren't there his girlfriend is. She is VERY loud in the bedroom, unnecessarily so, and sounds fake to me. It's always at the most random times too, 2am, 4am....when most normal people are trying to sleep to get ready for work the next day. I just don't know if this is something I can complain about, b/c frankly their sex life is their sex life...but it is interupting my sleep and sanity.