Biphasic Sleep, Day 1
It's great to finally be getting into biphasic sleep! Ati mentioned the goal of finding "a way to sleep which truly produces good rest and health in addition to any time or scheduling advantages" and I really think that biphasic sleep will be that way. It conforms to the body's circadian rhythm better than any other sleep schedule--even monophasic--and I think this form in particular (i.e. aligned with the 90-minute sleep cycle) will be much more efficient than monophasic sleep and much easier to adapt to than polyphasic sleep. The biggest question in my mind is whether this form of biphasic sleep is feasible in the 90+180 schedule (i.e. 90-minute nap and 180-minute core sleep) that I'm trying, or whether a person needs the extra sleep cycle that the 90+270 schedule provides. It might be situational--I could find that once adapted I'm normally energetic under the 90+180 schedule, but if I want to do intense exercise I need the 90+270 schedule. There are lots of interesting questions that I'd love to see answered through my experience and/or the experiences of the others here trying biphasic sleep.
On to the log: having gone to bed at 2am but not fallen asleep too quickly, I had a little trouble waking at 5am. I was conscious from the time my alarm went off, but in hindsight my thinking was very fuzzy. For some reason at 5:10am my mind snapped into focus, I turned off my (still-buzzing) alarm, and from there I was alert for most of the morning. After a few hours I did begin to feel a little sluggish. This was nothing compared to my experiences with polyphasic sleep--the tiredness only became significant twice during the day, and both times were quickly overcome just by getting up and moving around.
My nap at 2:30pm was pretty much ideal. I woke up easily when the alarm went off at 4pm, indicating that the nap's timing had worked with my sleep cycle. I was still sluggish for the rest of the night, but I expect this problem to fade away as my body adapts to the schedule.