how can i stop my 8 month old GSD from barking at night

It is probably seperation anxiety, Unfortunately I dont have any real solutions for you, apart from the usual things I would say to someone taking an 8 week old pup home, such as ticking clocks, leaving a lamp on, a peice of your clothing with your scent on it etc, but the pup has been doing it for 6 months now, have you tried any of these things?