I do not consume caffeine 
How come? It's the world's most widely consumed psychoactive drug.
I think I am just really sensitive to it. It makes me jumpy.
Ah yes, caffeine stimulates certain portions of the autonomic nervous system.
I wonder how long it has been around
I'm not sure, but caffeine is legal and unregulated in nearly all parts of the world.
I see some people drinking a few energy drinks a day. I think that is somewhat unhealthy.
Yea I would imagine so. Energy drinks are marketed as providing mental and physical stimulation.
Plus they have so much sugar
Yup. They may or may not be carbonated and may contain herbal extracts, taurine, and amino acids