I have no idea what the differences are, but today has gone significantly better than yesterday. As far as work is concerned, at any rate.
Yesterday, I could barely keep my eyes open, downing cup after cup of coffee, and part of me was practically begging 5:30 to arrive.
Today, I've had the same amount of sleep as yesterday, but am doing worlds better. I'm doing the exact same type of work but am not minding it nearly as much. I don't get it.
I'm not complaining, but I don't get it.