
Hi ;)
How long have they been sleeping together without any problems? Did you have them both from puppies? And finally.......sorry about all the questions ;) How long has George been barking at Izzy? And does he do it every night. How does Izzy react to him when he does this?
Is there anything that you can pinpoint that has changed in your household recently? Very often, if you ask yourself questions, you come up with the answers yourself :) There is nearly always a reason for a change in behaviour and I know from experience, it's not easy when you are so close to the situation to try and find a cure.
Is it possible, for the time being anyway, that you could seperate them at night? Perhaps he wakes up bored, knows that by barking, he gets yours and Izzys attention, so this in itself is rewarding for him. Or perhaps there is something that Izzy is doing that provokes him.
A camcorder would be very useful, then you could see exactly what starts him off :D
HTH