However, not everyone agrees with these unnatural sleep patterns. Dr. Piotr Wozniak suggests some negative long-term effects of polyphasic cycles, available here and a follow-up article available here. I have to warn you though, they are both very long (which is why I don't even bother to summarize them for you here).
You might also want to check out a cool iPhone Sleep Cycle alarm clock app that monitors your movement and wakes you up when you're in your lightest sleep phase. This could be useful since being awaken while in your deep sleep (REM stage) is proven to interfere your long-term memory.
|Sleep Cycle app screenshot|