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
Caffeine
Caffeine is a central nervous system (CNS) stimulant of the methylxanthine class. It is the world's most widely consumed psychoactive drug. Unlike many other psychoactive substances, it is legal and unregulated in nearly all parts of the world. There are several known mechanisms of action to explain the effects of caffeine. The most prominent is that it reversibly blocks the action of adenosine on its receptor and consequently prevents the onset of drowsiness induced by adenosine. Caffeine also stimulates certain portions of the autonomic nervous system.
Caffeine
. Other examples would be social drinking, nootropic, or sleep aids. Caffeine is the world's most widely consumed psychoactive substance, but unlike many others, it is legal and unregulated in nearly all jurisdictions. In North America, 90% of adults consume caffeine daily.
Psychoactive drugs are divided into different groups according to their pharmacological effects. Commonly used psychoactive drugs and groups:
- Anxiolytics
- Empathogen–entactogens
- Stimulants ("uppers"). This category comprises substances that wake one up, stimulate