More than 80 percent of American adults drink coffee daily in such mundane settings as the office and in the car that we often forget it’s the world’s most popular psychoactive drug. The Smithsonian’s Surprising Science article This Is How Your Brain Becomes Addicted to Caffeine, reports that scientists declared caffeine chemically addictive in 1994. The latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) included caffeine withdrawal as a mental disorder.
Caffeine is a naturally occurring chemical stimulant called trimethylxanthine, which in its pure form, is a white crystalline powder that tastes very bitter. Regular caffeine use alters your brain’s chemical makeup, leading to fatigue, headaches, and nausea for those who try to quit.
The article describes coffee withdrawal. Within 24 hours of quitting, withdrawal symptoms begin. Initially, they’re subtle: The first thing you notice is a mental fogginess, and lack of alertness. Muscles become fatigued, even when you haven’t done anything strenuous, and you suspect that you’re more irritable than usual. Over time, an unmistakable throbbing headache sets in, making it difficult to concentrate on anything. Eventually, as your body protests having the drug taken away, you might even feel dull muscle pains, nausea, and other flu-like symptoms.
The author explains the reason caffeine is addictive stems from the way the drug affects the human brain, producing the alert feeling that caffeine drinkers crave. Soon after you drink (or eat) something containing caffeine, it’s absorbed through the small intestine and dissolved into the bloodstream. Because the chemical is both water- and fat-soluble it’s able to penetrate the blood-brain barrier and enter the brain.
The article says caffeine closely resembles a molecule that’s naturally present in our brain, called adenosine (believed to play a role in promoting sleep and suppressing arousal)—so much so, that caffeine can fit neatly into our brain cells receptors for adenosine, effectively blocking them off. Normally, the adenosine produced over time locks into these receptors and produces a feeling of tiredness.
When caffeine molecules are blocking adenosine receptors it generates a sense of alertness and energy for a few hours. Additionally, Surprising Science notes some of the brain’s own natural stimulants (such as dopamine) work more effectively when the adenosine receptors are blocked, and all the surplus adenosine floating around in the brain cues the adrenal glands to secrete adrenaline, another stimulant.
For this reason, caffeine isn’t technically a stimulant on its own, says Stephen R. Braun, the author or Buzzed: the Science and Lore of Caffeine and Alcohol, but a stimulant enabler: a substance that lets our natural stimulants run wild. Ingesting caffeine, he writes, is akin to “putting a block of wood under one of the brain’s primary brake pedals.” This block stays in place for anywhere from four to six hours, depending on the person’s age, size, and other factors, until the caffeine is eventually metabolized by the body.
In people who often invoke this process (i.e. coffee/tea, soda or energy drink addicts), the brain’s chemistry and physical characteristics actually change over time as a result. The most notable change, the author says, is that the brain grows more adenosine receptors. This is the brain’s attempt to maintain equilibrium in the face of a constant onslaught of caffeine, with its adenosine receptors so regularly plugged (studies show that the brain also responds by decreasing the number of receptors for norepinephrine, a stimulant). This explains why regular coffee drinkers build up a tolerance over time—because you have more adenosine receptors, it takes more caffeine to block a significant proportion of them and achieve the desired effect.
This also explains why suddenly giving up caffeine entirely can trigger withdrawal effects. The underlying chemistry is complex and not fully understood, but the Smithsonian reports that your brain is used to operating in one set of conditions (with an artificially inflated number of adenosine receptors, and a less norepinephrine receptors) that depend upon regular ingestion of caffeine. Suddenly, without the drug, the altered brain chemistry causes all sorts of problems, including the dreaded caffeine withdrawal headache.
The article has good news, compared to many drug addictions, the caffeine effects are relatively short-term. To kick the habit, you only need to get through about 7-12 days of symptoms without drinking any caffeine. During that period, your brain will naturally decrease the number of adenosine receptors on each cell, responding to the sudden lack of caffeine ingestion. If you can make it that long without a cup of joe or a spot of tea, the levels of adenosine receptors in your brain reset to their baseline levels, and your addiction will be broken.
Related articles
Ralph Bach has been in IT long enough to know better and has blogged from his Bach Seat about IT, careers, and anything else that catches his attention since 2005. You can follow him on LinkedIn, Facebook, and Twitter. Email the Bach Seat here.
The I Love Coffee blog is written by Ryoko Iwata; a Japanese coffee-lover living in America and is full of infographics, facts, quizzes, and other fun visual stuff about coffee. Here are 20 facts worth knowing about coffee from I Love Coffee.
Have you ever wondered what gives 
Some will say a good night’s sleep or a hot breakfast is essential to start your day. However, Most people start their workday with a cup of coffee in the morning. This infographic ‘The Bond Between Work and Coffee’ by 