Does resetting the sim work for you? I had this problem yesterday (I'll try the game today again and see if it remains), and I thought it was because my sim put some item in the pocket instead of putting it on the table before going to bed, as that used to be a problem with the toddlers. Toddlers were always fixed with resetsim though, and I tried this on my sim and it didn't work.
It's in an apartment and the neighbours weren't noisy at the moment. Although, the night before the neighbours were noisy and I didn't get the option to bang on the door! I had to travel to another block with my sims and return and then it wasn't noisy any more. But I'm wondering if this is the same bug, that they can't sleep because the noise didn't end properly (by banging on the door or just waiting for them to become quiet).
I turned of the lights and put curtains on the window because I figured, maybe it's too light to sleep, but they're still awake. And no, they haven't had coffee and the mood isn't light green (I don't know what that mood is called in English).