My dog (2yo greyhound) wakes up every single morning between 5:45 and 6:15 and starts barking like crazy. Doesn't matter whether he sleeps in our room or in the next room. I've tried ignoring him and letting him bark but he won't stop and we have neighbours.. If I give him attention and play with him for a while he will stop and go back to sleep (and sleep like a baby for hours). I know that it's rewarding bad behaviour but I don't know what else to do. Any advice would be appreciated. Thank you!