Would it be possible to get him a friend? I have always had at least two just for this reason. I, too, have done the pretend-to-leave tests, and they settle in and sleep. I care for my sister who requires a treatment at a hospital in another city once a month, so they are left alone for about 6 hours that day. I do crate one, but the other is loose, in our mud room/breezeway. When we get home, they are both calm and yawning, as though we woke them up.