So what is caffeine, anyway?


Open up any social media app today and you will be bombarded with hashtags and Snapchat filters reminding you that today, September 29th, is National Coffee Day. And such an occasion would not be complete without a thorough investigation of the namesake’s key ingredient: caffeine. So, grab your favorite cold brew or dark roast and find out: what is caffeine?

Starting with the basics, caffeine is a naturally occurring chemical compound found in a wide variety of plants, containing eight carbon atoms, ten hydrogen atoms, four nitrogen and two oxygen. When ingested, the body metabolizes the caffeine, via the gastrointestinal tract, and absorbs it into the bloodstream. From the bloodstream the caffeine is carried up to the brain where it begins to take effect.

caffeine01The physiological sensations we experience after consuming caffeine are made possible by its near identical structure to a naturally occurring chemical in our body called adenosine. Adenosine is a chemical that prompts drowsiness in the brain when it binds to the brain’s adenosine receptor sites.

Caffeine, given its similar structure, binds to the receptor sites and effectively blocks them from accepting adenosine, therefore preventing drowsiness. This blockage is what creates the wakeful state that we associate with caffeine. The drug can also over-stimulate the central nervous system, causing those jitters and flutters that we sometimes feel as well.

So, how long does it last?

According to John Dopp, an associate professor in the Center for Health Services in the School of Pharmacy (who actually doesn’t even drink coffee himself), the effects of caffeine are on average felt around 30 minutes after ingestion and can last for up to six hours in the average body.

When the chemical is finished being broken down in the liver and filtered through the kidney, the effects of the drug wear off. In pharmacy, this is called a transient effect, or one that is temporary. However, over time, similar intake of caffeine will not produce the same increase in wakefulness.

This, according to Dopp, is the result of tolerance. Tolerance develops when the brain, blocked by caffeine, begins to manufacture more adenosine receptor sites to compensate for the caffeine blocking normal adenosine function. This means that the same caffeine intake does not produce the same increase in wakefulness it once did, and greater caffeine consumption is required to create the same increase in wakefulness.

It is common knowledge that the human body becomes dependent on caffeine if they consume enough on a daily basis and for a long enough duration. Withdrawal occurs if the body does not receive enough caffeine to block the adenosine sites, which are relatively… unpleasant, Dopp says.

“You’re going to become irritable, and you’re going to have headaches, and you’re going to become lethargic and you may also become drowsy to some extent.”

So if you’re taking a lot of caffeine per day, the best thing to do is to gradually decrease your intake to avoid the worst of the withdrawal effects, says Dopp. To avoid trouble sleeping, limiting caffeine intake within six hours of bedtime will help prevent any adenosine blockage.

“But, at the context of being at an academic institution, it’s a reality that many students drink caffeine to be at their best, to have the wakefulness to study effectively, and get their papers written in the evening hours,” Dopp says.

So, basically, everyone’s body is different, and effects can vary greatly. Happy National Coffee Day, and drink responsibly!