Drinking black coffee or mate in the morning, delayed until two hours after waking, enhances alertness and focus by leveraging the established circuits between the eye, circadian clock, and adrenals.

“but I delay it until two hours after I wake up and that's because I want the circuits between my eye and my and my circadian clock and my adrenals to be functioning in a particular way so that then later the caffeine is an addition it adds more alertness”