I'm two weeks in to a polyphasic sleep adaptation. I wrote a fairly lengthy blog post about it, but some details that might interest LWers:

1) I'm using a Zeo which is proving to be extremely valuable even just for my own sanity, because adaptation is hard enough without objective data that it's working. I've started informally trying to guess what my chart will look like after each nap (e.g. Wake, REM, REM, Wake (the bars represent 5 minutes)) and I plan to start doing so formally tomorrow. I expect to get to the stage where these predictions are quite accurate. Then again, I also expect that as I adapt, my naps will become more consistent.

2) I've been running myself through a battery of tests on Quantified Mind. No conclusions yet.

Unfortunately, with both the Zeo and QM, I didn't do much/any data-gathering before adaptation, because I only acquired / started using the technologies in the week prior to adaptation, and for logistical reasons I didn't feel like I could delay my adaptation for the month it would have required to get enough Zeo data and eliminate all of the practice effects on QM.

It's possible that at some point I'll be forced to return to monophasic. At this stage, the data I'm gathering may become more valuable, especially if I later return to polyphasic.

3) Moments of extreme tiredness have been an interesting exercise in Systems 1 and 2 fighting each other. My body / limbic system wants nothing more than sleep, but my neocortex is driven to succeed. I can watch them battle if I pay close enough attention.

If anyone has experiments etc. they'd like me to attempt, I'm open to suggestion, although they may not be feasible.