I don't consume caffeine anymore, I used to drink an entire pot of coffee every morning though!
You're one of a minority now.  Caffeine is the world's most widely consumed psychoactive drug!  Everyone's doin it man...
I know! It just made me way too shaky.
Being a psychoactive drug, caffeine can definitely have that effect on people.  It is a substance that changes brain function and can alter mood, perception or behavior.