I'll just leave this here.
http://www.collegiatetimes.com/opinion/columnists/article_65566b35-f4bb-5ac1-8b90-9551fe902d8e.html
''Hello, my name is Mark and I have a confession to make: I have a drug addiction. When I go a day without my fix, I develop withdrawal headaches and find myself wholly unable to function. There are times when I have become so dependent on it that I have gone on binges, after which I end up feeling ill and strung out.
I am not alone in this; my drug of choice is the most frequently used and abused psychoactive substance in the world. According to Canadian dietician George Malkmus, 80 percent of North Americans consume it on a daily basis. I am not talking about cocaine, adderall or methamphetamines. The drug I am addicted to is caffeine.
Let us briefly consider the chemical reaction of caffeine in the brain.
Caffeine is a central nervous system stimulant. It is structurally similar to adenosine, the chemical that is responsible for making you tired and regulating your sleep cycle. When caffeine is released into the central nervous system, it binds to the adenosine receptors and acts as an inhibitor.''
''Contrast caffeine with marijuana. The primary psychoactive substance in marijuana is delta-9-tetrahydrocannibinol, otherwise known as THC.
Throughout the brain there are cannabinoid receptors and neurotransmitters. What this suggests is that THC actually affects the brain in the same way a naturally occurring chemical does, so it does not physically alter one’s brain chemistry as most psychoactive drugs do.
The binding of THC to the CB1 receptors within the brain is what causes the psychological effects of marijuana, while the binding of THC to the CB2 receptors causes the majority of the physical effects. These effects can include muscle relaxation, euphoria, increased sensuality, paranoia, an increase in episodic memory and decreased short-term memory.
Unlike caffeine, most evidence suggests that marijuana is not physically addictive. Physical addiction to a drug is caused by the drug physically altering one’s brain chemistry in a way that nurtures dependence. For example, the brain is not accustomed to caffeine. The dependence one develops comes from his brain attempting to compensate for the unnatural chemical reaction.''
''A 2006 government report in the U.K. concluded that marijuana is less harmful than tobacco, alcohol and many prescription drugs. Furthermore, while it is true that there are many carcinogens in marijuana smoke, a 2006 UCLA study concluded that heavy marijuana smokers do not seem to be at an increased risk of lung cancer compared to non-smokers.''
Read more in the link.