My morning usually goes like this: I wake up, shower, eat breakfast, and drink coffee before stepping out of my apartment to face the day.

Depending on how much time I have in the morning, I may skip some of those steps. Next time you see me, ask me how hungry I am and whether my socks actually match. But there is something that I never skip: coffee. And I’m not alone in this ritual—54% of Americans older than 18 drink coffee every day.

Caffeine, coffee’s active ingredient, is something I can’t imagine cutting completely out of my everyday life. It wakes me up in the morning and helps me focus on my work in the lab. Caffeine’s seemingly magical ability is due to its stimulating influence on the brain. It temporarily increases brain activities by blocking adenosine, a neurotransmitter, to promote blood flow to the brain and suppress blood flow to the body. Increased blood flow to the brain triggers some of the reasons why we drink coffee: being more alert, focused, and awake.

My relationship with coffee is complicated. Although coffee is an integral part of my daily routine, I feel uneasy and even guilty whenever I drink too much. Maybe it’s because doctors and the media tell us that too much caffeine may be harmful. Or maybe it’s because my hands shake uncontrollably or I can’t sleep until 4 in the morning after drinking too much coffee.

Despite the wonderful effects of caffeine consumption, too much caffeine can cause a myriad of side effects—restlessness, upset stomach, and fast heartbeat—and these symptoms can lead to more serious concerns. For example, overconsumption of caffeine can result in insomnia, even if one strictly follows the “no coffee after 2pm” rule. Caffeine has an average half-life of 5.7 hours in healthy adults, meaning that if your last sip of coffee was at 2pm, half of the caffeine from that sip is still circulating in your body around 8pm and a quarter of it at 1am.

If a person suffering from caffeine-induced insomnia decides to wake up with more caffeine rather than getting more and better sleep, s/he can fall into a toxic cycle. S/he will drink more coffee to stay awake, resulting in insomnia and sleep-deprivation, which are fought with more coffee leading to worse insomnia and sleep-deprivation. And we know sleep-deprivation can be harmful for your health in the long run.

So at this point, you might wonder why I still drink coffee in spite of the possible harmful effects. I think this image from Jorge Cham’s “Piled Higher and Deeper” summarizes why (and I am only slightly joking):

Caffeine undoubtedly can help us be more alert and focused in the morning and throughout the day. For someone like me who has to constantly focus on details, read about and understand difficult concepts, do intricate tasks, and multi-task, caffeine may be the Holy Grail.

Plus, research studies have shown that moderate intake of caffeine is linked to lower risk of many diseases and conditions: heart disease, liver cancer, Alzheimer’s, and suicide, just to name a few. These studies do not conclude that the lower risks were directly caused by caffeine intake, but rather a healthy lifestyle. But maybe this means drinking coffee and living healthily aren’t mutually exclusive.

Currently, doctors agree that moderate consumption of caffeine is okay for adults—which is 400 milligrams of caffeine per day, roughly equivalent to four brewed cups of coffee. When the caffeine consumption exceeds that threshold, a person might experience unwanted side effects like the ones mentioned earlier.

Of course, this depends on how fast your body metabolizes caffeine or how accustomed your body is to caffeine, so that amount will vary among people. People who aren’t used to drinking caffeinated drinks can experience stronger side effects.

The side effects are stronger and longer-lasting for those who cannot metabolize it as efficiently, too. The half-time can increase from 5.7 hours in an average adult to 60 to 168 hours in an individual with compromised liver function (as caffeine is broken down by the liver). The half-life is changed also by pregnancy. According to one study, the half-life was almost three times longer for women in their last four weeks of pregnancy compared to non-pregnant women.

The final verdict seems fairly simple. Like many things in life, caffeine is great in moderation. Too much caffeine will not only give you unwanted side effects, but it can also be fatal. There have been reports of caffeine addiction and even death resulting from an overconsumption of caffeine in forms of energy drinks and caffeine pills. There are now efforts in raising awareness of how caffeine can be harmful to health; organizations like Caffeine Awareness Association (CAA) dedicate themselves in this endeavor. CAA has designated March of every year as “National Caffeine Awareness Month.”

For those who are interested in reducing their caffeine intake without cutting it out completely, there are some tips online to help you get to your goal. As for me, I will balance by sipping on my decaffeinated coffee, espresso drinks, and green tea—all have less caffeine than regular brewed coffee—to get through my day. In fact, I drank a cup of espresso while writing this post. Happy National Caffeine Awareness Month to the cognizant coffee lovers!

About the author

ireneSo Hae (Irene) Park is a fourth-year Human Genetics PhD student at the University of Michigan Medical School and a MiSciWriters Senior Editor. Before attending UMich, she received her BA in Biological Sciences and Philosophy at Cornell University. Now under the joint supervision of Drs. Thomas Wilson and Thomas Glover, Irene is investigating what causes genome instability—an accumulation of mutations in the cells—and how it can be avoided. Genome instability is commonly seen in many human diseases, like cancer. When she is not working during the wee hours in her laboratory or writing about the latest cool topics in science and medicine in The Michigan Daily or HIPPO Reads, Irene likes to watch movies, watch The Food Network, collect anything cute, learn how to make different types of coffee drinks, listen to music, travel, and read. Follow her on Twitter (@S_Park89).

Read all posts by Irene here.

2 thoughts on “Coffee: To drink or not to drink, that is the question

  1. I wonder if there is any research on caffeine and focus. I find that when I have caffeine I become more productive, but that it’s more difficult for me to harness my attention to one task.


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