Having just woken up from my second 3-hour sleep (hence beginning day two), I thought this was the best time to summarize my first day experience.
Getting up at 4am to begin the day wasn't inordinately hard, much like getting up early to catch a plane. I endured the standard "up too early" tiredness up until my 8am nap during which I did manage to get a very small amount of sleep. After the nap I felt genuinly more refreshed for an hour or so, but the standard low-level tiredness soon set in and by 1pm I felt ready for another nap, during which I again got a small amount of sleep.
After the 1pm nap I felt slightly more woozy than I did at 8pm, but after that passed I was more or less normal for the rest of the afternoon/evening, including being too awake to get any sleep during my 7:30 nap (which I changed from 9pm when I realised 7:30 was a more balanced time). By the time 1am rolled around I felt just tired enough to sleep and as far as I can tell, slept smoothly up until the alarm went off at 4. Getting up this morning was a little harder, but certainly not unmanagable. I'm curious to see how tired I feel throughout today, and how I feel after my next core sleep.