Around the time I began experimenting with polyphasic sleep, I began keeping a log of when I was actually going to sleep. Since days were blurring together, a record of my naps was very useful in trying to translate how my waking hours mapped onto days as the rest of the world experiences them. The blue areas represent time I went to sleep. The dark blue represents time I recalled dreams upon waking (and therefore know for a fact that I had achieved REM sleep).
I believe this log was also helpful in formulating the hybrid schedule that I am attempting now. Looking at this graphic, there were a few things I noticed right away. I was struggling to staying awake in the wee hours of the morning, while having almost no difficulty during my traditional waking hours. I also noticed that I remembered my dreams upon waking most often at 8am. Sometimes I would recall dream in the earlier hours of the morning, but never during the day.
I combined this information with the subjective observation that I wasn’t accomplishing anything useful or entertaining during the early morning hours that I fought to keep my eyes open. It was pretty intuitive, then to imagine getting a sold chunk of sleep from midnight to 4:30am (estimated 3 or maybe 4 REM cycles) and hang onto a couple of naps. 8am is an obvious choice because of the known success I’ve had hitting REM. Noon was chosen as the second nap time largely because it is easy to slip out during lunch when I am at work.
Note that the dark blue areas are almost certainly not the only times I reached REM sleep. Those are simple the times I remembered a dream upon waking. Particularly in the stretches where I was asleep for several hours, I’m confident I had one or more REM cycles. It’s likely that some of the 30 minute stretches that appear the lighter shade of blue covered areas of REM sleep that I just can’t verify.