The best times to drink coffee are when your cortisol levels naturally dip. These are, in fact, traditional “coffee break” times.
Iwata, as her blog title suggests, loves coffee and has articulated what she considers to be the optimal timing of your coffee intake to experience maximum enjoyment with minimal negative effects. The times of peak cortisol levels in most people are between 8-9 am, 12-1 pm and 5:30-6:30 pm. Therefore, timing your “coffee breaks” (an apt term) between 9:30-11:30 and 1:30 and 5:00 takes advantage of the dips in your cortisol levels when you need a boost the most (see graphic by Iwata below.)