@Funkdaddy: Pavlina explicitly said that it wasn’t for health reasons or lack of sleep but just for social things (wanting to spend more time with his wife, the rest of the world not being polyphasic etc). Like Bucky Fuller it was more a case of giving up because he had to fit in with other people’s schedules.
Furthermore there’s examples of Everyman schedules proving to be more feasible for living in a Monophasic world, with this blogger being Polyphasic since 2006 (having been so briefly before):
http://www.puredoxyk.com/
Studies in Polyphasic sleep are inconclusive. So far they suggest Free-Running Sleep to be more effective but I don’t know of anybody who truly has a FRS schedule. Further, from what I’ve read, there does seem to be some argument for saying Polyphasic is better than a non-FRS Monophasic routine. It’s an area that needs more through research for sure. So far scientists just seem to be dismissing it without research.
It’s patently incorrect to say it’s not natural. The evidence cuts both ways (and there’s not much either). As for if it’s healthy, there’s little evidence in either way. That’s part of the attraction; it’s an experiment.
To be fair I don’t know anyone who proclaims it to be healthier than Monophasic. Most say the extra hours are worth the risks (especially as the risks aren’t at all clear). Besides, most people have sleep debt anyway, some have it even when sleeping the recommended 8 hours.
Of course it isn’t for everyone, and if you have no want/need for extra time in the day then you may not find it at all useful. Some people just need a siesta in the afternoon, and other can survive with just a solid block of sleep at night. We’re all different after all.
Ultimately the only way to know about it is to try it (at least until we actually get scientists willing to dedicate the necessary time to explore it properly, not simply dismiss it). We’re constantly told that our sleep patterns vary, that no two people have the same sleep rhythms. If you want to try it, try it, if you don’t, don’t.