Originally Posted by silicon toad2000
that fatigue sounds like you were woken out of delta sleep, or woken in the middle of a sleep cycle.
From the sounds of it your core sleep was 7 hrs 15 minutes.
I'd suggest that perhaps for a bi phasic sleep pattern that your core sleep is too long. try setting your nap for 1.5 hours and your core sleep for 6 hrs for a total of 7.5 hours.
This eliminates the most attractive benefit of biphasic sleeping: time. I already sleep 7.5 hours monophasically. It would be life-changing to be able to stay up late and get up early, like many of you seem to do.
... that your core sleep is too long
I think I see where the confusion came from. My core sleep was only scheduled for 4.5 hours. I was supposed to get up at 9:00 AM. That's right. I reset my alarm every 30 minutes for over two hours.