Worth adding that there is great variability of the half-life of caffeine in different people, in part due to different phenotypes of the enzymes responsible fo

Worth adding that there is great variability of the half-life of caffeine in different people, in part due to different phenotypes of the enzymes responsible for its metabolism (among other variables). For instance, I metabolize it slightly slower (if you can trust 23andMe SNP data enough for that kind of a prediction), so it could be even longer for me. iirc nicotine has also been shown to speed up caffeine's metabolism.