Noisy building

It never used to be like this. In the past few months just about all the residents of my apartment building have moved out (there are 8 units here) to be replaced by some of the noisiest neighbours ever.

Last night two girls from one of the downstairs units decided to have a loud conversation on their balcony...at 3:30am. Tonight, another downstairs unit is (at the time of writing) into the 11th hour of their party. It is now 10:54pm with no signs of it abatting. The other week, some other residents on the very bottom floor started a party at 4:15am on a Sunday morning. Is that really the most appropriate hour to begin such a thing?

Living in an apartment building, one must accept loud parties as a matter of course. But really, this is becoming rather unreasonable. The quietest room in my apartment is the bathroom, but I don't fancy curling up in the bathtub when the temperature is currently 6 degrees.