I'm deeply skeptical about these massively shortened sleep cycles too, but to be fair, Steve Pavlina gave it up for the same reason Dyson did; it's too hard to interact with the 'awake-during-the-day, asleep-during-the-night' crowd, not because "it didn't work" for him.
I never bought that excuse. There's zero scientific evidence for breaking a habit humans and our ancestors have been doing for literally millions of years. "Social interaction was hard" seems like a face saving excuse for "I wasn't able to beat evolution."
FWIW, evolution actually is telling us to do biphasic, not the current monophasic. We slept biphasic right up until a century or three ago, and the literature documents this pretty well. Let's see, to pull my canned refs from my melatonin article (http://www.gwern.net/Melatonin); we have Stampi in _Why We Nap_:
> “It is worth mentioning that anthropological studies conducted in tribes active at night show that human sleep can be highly polyphasic in certain cultures. Although they have different cultures and ways of life, both the Temiars of Indonesia and the Ibans of Sarawak have similar polyphasic sleep-wake behaviors (Petre-Quadens, 1983). Their average nocturnal sleep episode duration ranges between 4 and 6 hr, and nighttime activities (fishing, cooking, watching over the fire, rituals) at any one time involve approximately 25% of the adult members. Daytime napping is very common in both tribes: at almost any time of day, about 10% of the adult members are asleep. Whatever the cause of these polyphasic sleep patterns,whether the expression of an inborn ultradian rest-activity tendency or other factors, such populations exhibit extremely flexible and fragmentary sleep-wake cycles. The minimal contact with modern civilization could be one of the reasons for the preservation of this possibly ancestral sleep pattern.”
And then, for all the European examples, see http://www.historycooperative.org/journals/ahr/106.2/ah00034... The author apparently has a book on the same topic which I really ought to read, but the preceding is the article mentioned on his profile-page:
> _At Day’s Close: Night in Times Past_ (W.W. Norton, 2005), a sweeping study of nocturnal culture before the Industrial Revolution, which garnered four prizes, including an award given by the history honor society Phi Alpha Theta for the “best subsequent book” in all fields of history. His article in 2001, “Sleep We Have Lost: Pre-Industrial Slumber in the British Isles,” in the American Historical Review, earned two awards, including the James L. Clifford Prize given by the American Society for Eighteenth-Century Studies.
Sure. What this amounts to is sleeping at night, maybe going to bed late or getting up early and taking a nap during the day. We all want to take a nap at about 1:30 in the afternoon or so, up to about 6 you actually get to do it, too. But "taking a nap" is really different than "structured polyphasic sleep" that Pavlina more or less made up.
