My dog barks at me all the time.?

I have a 7 1/2 month old male neutered lab. He barks at me all the time. When i am gone he is crated. He doesn't bark when i leave. I stand outside the door before leaving and when coming home and don't hear barking. When i am home, however he barks at me constantly. He gets 2 good walks in a day plus i play with him and his toys. He doesn't have to go to the bathroom and his food/water needs are met. Every hour and a half or so he will just bark at me (wanting to play-he will do play bows and run around with toys). I know labs are hyper but this is nonstop. Each barking episode lasts about 20 minutes. and he is getting worse. He now barks in the middle of the night wanting to play. I try to ignore him and never play with him when he misbehaves. I am waiting to hear back from my vet about this. But has anyone had any situations simlar to this? Does anyone have any suggestions on how to correct this? He is driving me crazy. I can no longer do any work at home.