Why do people scream like they're being murdered?!

My neighbours are the WORST. They get drunk and party several times a week and they SCREAM and shout and their dogs go crazy like they've got an intruder or something. This happens ALL the time. I did actually shout at them one night for the noise (at 1am on a Thursday, I complained about them here that night too). I just don't get it.... Where is the decency to the neighbours? I know the people across the road from them work Saturdays as well, as does my husband and I *think* the people next to them too (I've seen them leave around the same time a my husband but maybe they're just going to a class or something).