I did an uberman polyphasic schedule for a year and everyman for about 6 months. Stage N1 is likely an adjustment period where your body rhythms slow down and things get ready. Studies have shown that stage N2 and N3 (deep cycles) are essential for healing and muscle growth- they are also when HGH hormones are released. REM has shown to be essential for memory retention and some studies have linked lack of REM to schizophrenia and other psychosis.

When I was polyphasic, roughly 70% of my polynaps were REM and 30% were deep cycles. Interestingly, if I was sore from a workout or something, it would continue to be sore until I had a deep cycle.

Despite the vast, vast multitude of sleep studies (and departments, and journals) out there, I've only seen one study on polyphasic sleep and it was very exploratory. People who study sleep at all immediately associate it with sleep deprivation, which has been studied so much all they can do is spew forth the negatives (there are tons) associated with it. The premise of functional polyphasic sleep is that the body actually adjust so there is no sleep deprivation.

I didn't end up blogging about it, and I don't write about it much, because frankly, after doing it for a month or so- when I was really well adjusted- I ceased having something to prove. It kind of feels like talking about my bowel movements or something. I guess it could be vaguely interesting to someone, but it bores the crap out of me (forgive me).

So quickly: I would not recommend it. You can't exercise much, the adjustment period is very, very difficult (only 10 days, but that's 6 naps a day == like getting up way earlier than you wanted to 60 times in a row. Most people can't even get up earlier than they want to once in a row.) You need an environment where you can have all the lights on and make all the noise you want all night. You can't have other people imposing meetings or any kind of schedule on you. You can't do anything that takes longer than 4 hours. And here's the real kicker: you can't work for more than ~50 hours a week without getting burned out! Yeah, having more hours doesn't help that. And don't even think of starting it if you have something remotely stressful coming up or not enough to do. And don't think of starting it if you live somewhere where it's cold at night. Etc.

All the debate over the health effects are meaningless- it's people who haven't experienced it or frankly studied it. Sleep deprivation only applies in the first 10 days. After that it feels far less harmful then, say, caffeine. shrug

EDIT: Hypothesis (in case someone actually wants to _study_ it- I sure couldn't find any takers when I was doing it): The body seemed to eliminate N1 altogether- my heartrate and body temperature would drop within 30 seconds of lying down- for over a year. 2nd part of the hypothesis- the the first one or two REM cycles at night are essential and the rest is padding built in by evolution to keep you asleep until dawn. 3rd part- other body functions relying on the circadian rhythm adapt- especially digestion, which is _totally_ different when fully adjusted to polyphasic sleep. 4th- there is a reservoir of... something... built up for when you get injured or sick by having that extra sleep in monophasic sleep.

Also, I stopped because I got lazy.

Finally, if you get colds easy, don't even try. A single cold will wipe you out for a day or more.