I play a handful of 3-minute games of Quordy (Boggle, basically) on my iPhone right after waking up. If my scores trend > 60, I'm in the "rested and aware" day

I play a handful of 3-minute games of Quordy (Boggle, basically) on my iPhone right after waking up. If my scores trend > 60, I'm in the "rested and aware" day. If I trend < 40, it's going to be a brain-fog day. I don't often fall in the middle, so I have found it to be a rather significant indicator.