I don't want to crash the party, but I've read research done on this subject. It's near and dear to me because I've had pretty unique sleep compared to anyone I knew. Really deep, never woke up on time for stuff, sleeping through hours of an alarm, being awake and sleeping at weird times of the day, etc. On that second point, I actually just gave up trying at some point because being sleep deprived < anything going on that day.
Anyways, research says we are biphasic. It's not natural to be polyphasic, and it was really not a healthy or happy path to go down. I have actually gone from generally monophasic to biphasic since I've been really, really ridiculously healthy (and good looking). So that's all I'm going to say... you've been warned.