He's made a reasonable historical case for the commonness of a split cycle sleep. However, I wanted more evidence, so I looked to an ancestor: research on chim

He's made a reasonable historical case for the commonness of a split cycle sleep. However, I wanted more evidence, so I looked to an ancestor: research on chimpanzees in wild seems to indicate that they start their days at dawn, and sleep mainly uninterrupted through the night... Did humans really diverge that much? I suppose further studies will tell. (After all, the creative differences seem undeniable, anecdotally...)