Interesting experience. I have found I can save time by poly-phasic sleep, but I find the 7-8 hours a night plus a short power nap in the afternoon most comfortable. 30 minutes is just a nap though, are you planning to make that second phase longer? Some even sleep 4 times, 1 hour each. (Was it Tesla?)

Isn't it true that until the Industrial Revolution humans slept in two parts? That's very recently! Some speculate the likes of Shakespeare were at their creative best between the two phases of sleep.