Soon, this can make you ask, “How much coffee is too much?” At the same time ... lowered for others with extreme sensitivity. Studies have found that some people may have a gene that makes ...

And that can have detrimental effects on daytime function, the authors report. Dr. Albert Ahn: It's sort of just stuck in this loop where you're not sleeping because you drink too much coffee and ...

On the other hand, too much caffeine can make it ... or even diarrhea in some people. Since coffee can have major effects on digestive function, you may want to cut back on the amount you drink ...