Make sure the dog's well exercised before you leave. Some dogs will naturally pine for their owners, but a tired dog is a dog more likely to want a nap.
Consider training a down stay in or near where you are. Dog pheromones or rescue remedy or vetricalm may also help since you are changing all the rules on him (not that it's bad), just be patient and consistant. He has learned that whining gets him what he wants.
