As an observer, I appreciate the debate, and I'll add that it doesn't seem to me like you're talking past each other. Giving the other gentlemen the benefit of the doubt that he's something of an expert on this subject, it seems he's very clearly understanding your point and offering his opinion to the contrary.
I, myself, have nothing much to add in the way of hard facts, but using logic, I think that sleep-as-an-energy-saver seems off. Sleep seems like a highly vulnerable state for early animals. If the only initial benefit of sleep was energy conservation, it seems like animals that simply chose to rest would have an edge upon those that slept. By resting, they'd conserve the same energy, but would stay alert and responsive.
And it interests me that animals that cannot rest (sharks, for example) still sleep.
I, myself, have nothing much to add in the way of hard facts, but using logic, I think that sleep-as-an-energy-saver seems off. Sleep seems like a highly vulnerable state for early animals. If the only initial benefit of sleep was energy conservation, it seems like animals that simply chose to rest would have an edge upon those that slept. By resting, they'd conserve the same energy, but would stay alert and responsive.
And it interests me that animals that cannot rest (sharks, for example) still sleep.