That's exactly how I discovered the über-early cycle... I stayed up later and later, one day 8am arrived and I wasn't even slightly tired. I knew I couldn't sustain that sleep cycle (waking at 4pm feels grim) so I pushed my sleep cycle forward, living 26-hour days.

I'm drifting forward (woke up at 7am today), I may be cursed with an inability to sustain a healthy rhythm at one specific time. Not sure yet.