I have a slight suspicion that every time I consume something with caffeine it has a specific effect on me.
A good cup of black or green tea: Slight headaches at some times.
A cup of coffee (from work coffee machine): Depending on strenght slight attention issues or headaches.
A cup of coffee from a coffee shop which roasts its own coffee: One time a bit of stronger attention issues than the work coffee.
I usually notice it right away after consuming.
But I also have a very strong issue with staying hydrated.
Usually drink 0.5-1l per day until I notice the usual dehydrated-headache or when I am really focused and loosing it at times.
Usually it’s less prevelant at evening/night times.
Decaf coffee has small amounts of caffeine in it. Not any noticeable quantity (to your average person, that is), but if someone is caffeine sensitive they may notice issues from it.
Hmmm still weird that the caffeine in tea doesn’t trigger it. I tend to drink quite a lot of tea because I can’t drink coffee, yet I tend to have no problems.