Polyphasic sleep update - is it possible to go backwards?

Just when we were being very awake and not allowing ourselves to go back to bed (me at least), a new round of tiredness has ensued in the last two days, much like that of the second week. In the early morning periods, from 4-8am, I'm extremely groggy again and have trouble staying up. I can get out of bed, but I can't really stay there with my eyes open. Also I've had a few groggy periods between the 8am nap and about 10.15 - I looked at my watch yesterday, and right on 10.15am, I could literally feel my energy levels and alertness rise to normal.

I partly attribute my early-morning grogginess to firstly having a slight cold, secondly missing a nap two days ago, and thirdly just not expecting to be tired and thus surprised by it. We didn't expect full adaptation to take this long, and so we hadn't est aside enough disturbance-free schedule time. But we've both been pretty tired in the morning, so I'm not sure about Brendan.

Lucky Everyman sleep is so forgiving when moving nap times around - I find I can move them around at least an hour or so, and in fact I should really keep them consistent and stop moving them by over an hour.

I think we've changed something and not realized it, to go backwards. I don't think this is normal for other people. Part of it is that I have a timetable which isn't constant, like Brendan's is most of the time, and so I spend a lot of time being very late for naps or slightly early.

Workarounds: yesterday Brendan and I each had an extra 20-min nap at approximately 6am, and a 5-min nap on the couch around 9am. Today we added an extra hour to the core nap and had a 5-min nap at around 6am. I think that's fixed it now.

Once Brendan finishes his major current work project, around early July, we plan to experiment for at least a month with moving the core nap to 4am to 7am and keeping the rest of the naps mostly the same (last one around 11pm). While it has some obvious disadvantages, and I really like having time in the mornings, this timetable would be closer to our student sleep timetable (and placate our friends).