The Brain on Coffee

I recently became a coffee drinker, and as I drank my coffee one morning, enjoying how much more awake and alert I felt with every sip, I began to wonder: why does coffee help me wake up and focus? What is caffeine doing to my brain?

Photo by History Underfoot, Used with permission.

Energized by my morning brew, I jumped right into research. Soon I learned many new words (neuroscience papers are superfluously verbose) and why coffee helps most of us feel more human on even the least promising morning.

A drawing of the brain.
A public domain image. Source.

The invigorating effect of coffee can be traced to the caffeine present in the beans. We all know that caffeine is a central nervous system stimulant. But how does it get into our nervous system in the first place? Caffeine can easily cross the blood brain barrier, a screening system which prevents most chemicals from entering the brain, to interact with our neurons. 

Stained neurons.
A creative commons image. Source.

What does that mean?

Before I explain exactly how caffeine interacts with our neurons let’s back up a little and briefly review how our brain works. Our brains are made of neurons which respond to stimulus by sending and receiving neurotransmitters. Neurotransmitters are chemical messages which either trigger neurons to release more neurotransmitters—or stop neurons from releasing more neurotransmitters. The complex patterns of releasing and withholding neurotransmitters are what allow us to move our muscles, to make decisions, and form memories.

A creative commons image. Source.

One end of a neuron—the end which receives neurotransmitters—is made of many branched extensions called dendrites. The dendrites are covered in receptors which interact neurotransmitters. Different types of receptors respond to different neurotransmitters. 

Now, let’s get back to the coffee. Caffeine mainly affects two types of receptors known as the A1 and A2A receptors. These receptors normally receive adenosine, a neurotransmitter which helps us sleep and relax. Caffeine blocks the A1 and A2A receptors and prevents them from receiving adenosine. With less adenosine interacting with our neurons we automatically feel more alert and awake. 

Drawing of neurons.
A public domain image. Source.

Caffeine,  in preventing adenosine from doing its job, has a few side effects like increasing anxiety. People who are prone to anxiety and panic attacks—and first-time coffee drinkers—are more likely to feel nervous after a cup.

Luckily for us regular coffee drinkers, most people’s brains habituate to caffeine very easily, and the caffeine jitters become less pronounced the more frequently one drinks coffee. After my first cup of coffee, I felt a little on edge, but now that I’ve been enjoying coffee daily for about two weeks, I don’t feel nervous after my morning mug.

Vintage coffee can.
A creative commons image. Source.

Caffeine promotes alertness, which is great during the day, but not as pleasant at bedtime. Even if one does manage to fall asleep after drinking coffee in the afternoon, caffeine reduces the amount of deep sleep per night and increases the amount of light sleep. The rapid eye movement (REM) sleep, or dreaming sleep, remains the same regardless of coffee consumption. First-time coffee drinkers are more likely to experience sleep disruption as increased caffeine tolerance reduces the drug’s influence on sleep.

Another thing I learned is exactly how quickly one becomes accustomed to caffeine depends largely on genetics. Some people’s livers metabolize coffee slowly, and since caffeine would remain in their bodies longer, it may have a stronger effect on them. In general, people of Asian and African descent tend to metabolize caffeine more slowly than those of European descent. 

Author's own image.

I have not gotten my DNA sequenced yet, but I’m guessing that my liver metabolizes caffeine fairly quickly because I quickly became habituated to caffeine and my ancestors were European.

Coffee has a few other side effects like excessive urine production, increase in systolic blood pressure, and dilation of the airways. I’ve read that drinking too much coffee can raise the blood pressure to dangerous levels in people with hypertension. (Always do your own research.)

Author's own image.

For people without hypertension or caffeine-induced anxiety, lifelong coffee drinking is suspected to delay the onset of cognitive decline, Parkinson’s disease, and diabetes. One recent study found that drinking coffee reduced the risk of brain tumors in Japanese populations. The benefits of coffee drinking tend to be more pronounced in women.

Unfortunately, these health benefits only apply to lifelong coffee drinkers. Starting to drink coffee as an older adult can possibly increase cognitive decline. People with Parkinson’s disease and diabetes who began to drink coffee after they were afflicted reported no change in their symptoms.

Even if coffee can’t change the symptoms of Parkinson’s or diabetes, it can improve one’s mood. Coffee paired with bread and blue light is one of the top mood improvers! I know next time I’m feeling down try this coffee, bread, and blue light strategy. (Where do I find blue lights?)

Coffee and bread, my breakfast this morning! Author's own image.

Happy coffee drinking to my fellow coffee lovers!

Inspired to learn more about coffee? Check out my post on my other blog, Totally Baroque, about 17th century men and women who couldn’t pass a day without the “drink which drove away drowsiness" here.

Sources.