Interesting, either the store is selling you fake decaf, or there's really a whole bunch of other chemicals, other than caffeine, that can mess with your body.
I have an unusually strong response to caffeine (a cup of coffee, strong tea, or, on a bad day, even a small glass of Coke). It doesn't really affect my heart (as far as my Apple Watch can tell), but it obliterates my sleep and makes me feel quite a bit more anxious than usual. Decaf coffee solves the problem completely — no stimulation, no anxiety, normal sleep. Coincidentally, I had a tall glass of iced decaf just two hours ago, and I'm going to bed in a few minutes.
Everybody is different. I'm sensitive enough to caffeine that trace amounts causes anxiety. I have to avoid chocolate.
I'm equally sensitive to alcohol. Because it's immediately absorbed into the blood, a sip of scotch will take out my antidepressant in seconds. It's shocking how quickly and how severely even a small amount of alcohol affects me. It's almost like an allergy.
I have an unusually strong response to caffeine (a cup of coffee, strong tea, or, on a bad day, even a small glass of Coke). It doesn't really affect my heart (as far as my Apple Watch can tell), but it obliterates my sleep and makes me feel quite a bit more anxious than usual. Decaf coffee solves the problem completely — no stimulation, no anxiety, normal sleep. Coincidentally, I had a tall glass of iced decaf just two hours ago, and I'm going to bed in a few minutes.