I guess it depends on the situation... I have a similar problem... but I don't want to put a bark collar on Jenny, because she is a good guard dog {considering she is just over 30 lbs} I have just stopped using her as a guard dog at night, I just close the door to my room with Jenny inside with me, so that she doesn't hear animals or walkers... {SOME DUDE ALWAYS WALKS AROUND OUR NEIGHBOURHOOD AT 4:00 AM }

If you don't wan't to put a bark collar on her, or lock her in your room...I don't know what to tell you.

You could try squirting her with a water gun... I've never tried that though because I am always too tired to get up in the middle of the night to squirt her. If you happen to be up with a water gun handy you should squirt her. I know with Jenny the water gun works perfectly for barking outside during the summertime, it distracts her from whatever she was barking at. Don't think I'm cruel I never squirt her in the wintertime... it would take her about 1 minute for her coat to freeze!

Whatever method you choose, good luck!