So true.

That would be a combination of not being addicted to caffeine (so you are not in need of a fix) and the better REM sleep you had prior to waking up.

In my opinion!

my pet hypothesis is that caffeine catalyzes energy consumption, at the expense of efficiency. that is to say, drinking a cup of coffee in the morning makes me a good worker for 1 hour, then i pay the price over the next 5-7. in contrast, no caffeine means a slower start, but more total "energy" towards work gets produced. basically, i dont think you can top natural energy regulation.