I have friend don't drink coffee because he has acid reflux and high blood, he could not sleep if he takes coffee then his high blood will be affected too, but one day he feels jealous looking at me enjoying coffee and he make his own black coffee too, lucky it's a morning does not affect badly to him but he has a bad headache, I feel relieve when he could rest after 18 hours. after that when we meet, I always remind him what happen and keep on reminding him to don't be hero, I still thankful his acid reflux doesn't go along or else its really worse experience.