Weird WBTB experience

I set my alarm as per usual for 3:30 AM.

I've WBTBed enough to know that its never pleasant getting up at that hour, and that 3 out of 4 times I lack the willpower to try my WILD attempt.

However, the other night, my alarm goes off and I wake up feeling.... normal.

I don't even feel tired, depressed, anything that usually comes with waking up. I feel as normal as I would mid-day. I don't even bother turning on the lights to wake up, I already feel wide-awake. I lay back and attempt to WILD for about an hour, but I feel too awake to fall asleep. I then just decide to turn on the lights and read until morning.

Is there a particular phase of sleep that I woke up during that would account for this? Was it just me being too energetic or something?

Any insights would be appreciated.