[Joe]

Think I'm getting old. I quit coffee a few weeks ago. All of a sudden, I started becoming more sensitive to caffeine - it made me very nervous.

Back in the day, I used to make this stuff called "fishing tonic" a thermos of sugared coffee with several No Doze tablets ground up in it when pulling all-nighters.

Now coffee brings on an anxiousness feeling that is not pleasant.
I guess it's fairly common.