Did you ever figure out what was causing the night-time aggression? We are having the EXACT same problem with our 4-year-old doberman. He is sweet as can be all day and cuddly, etc. with my boyfriend all day until the evening... he gets aggressive towards him... and it doesn't seem to matter if we are in the bedroom, kitchen, living room, or what we are or aren't doing. It's so strange! We are feeling pretty helpless since we don't know what is causing it!