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Frankly Health

By Students for Students


cup of coffee with coffee beans.

How is Caffeine Affecting Your Body?

by Casey Wayrynen

November 2, 2017

Coffee is good for you, right? Many adolescents and young adults, especially college students, consume a lot of caffeine throughout their years, but what they don’t know is how it helps them to survive those late-nights studying or long days at work. Caffeine occurs naturally among several plants such as coffee bean, kola nut, tea leaf, and cacao seed1. Just about 80% of adults in the United States consume caffeine, whether it is in foods, drugs, or beverages2. According to the FDA, it is considered both a drug and a food additive3.


Caffeine is a central nervous system (CNS) stimulant which causes alertness and gives a boost of energy when consumed4. What causes these feelings is the release of neurotransmitters and their chemical effects on the brain.  Adenosine is one of these neurotransmitters and it acts as the “brakes” in the CNS so when its effects are blocked, in this case by caffeine, stimulation happens1. Within an hour after consumption, the caffeine is rapidly absorbed into the circulation of the body and its effects last about 3-5 hours 2. Along with energy and alertness, there are some drawbacks such as feeling tired, jittery, having headaches, and dehydration4. Dehydration is a very common side effect because caffeine is also a diuretic that causes the body to lose water3. To sum it up, caffeine’s purpose is to prevent the body from slowing things down1.



Many factors are involved when it comes to determining how much caffeine is enough. There is a wide variety of benefits and risks that are attributed to caffeine. For healthy adults, daily consumption of up to 400 mg will not present any health risk2. When it comes to keeping you up after sleepless nights, studies have shown that caffeine consumption in low doses will help increase alertness whether someone is fatigued or well-rested. High doses of caffeine are more likely to result in anxiety, while low doses are more beneficial2. Lifestyle, age, and weight have an influence on an individual’s response to caffeine2. Sensitivity differs between age groups when it comes to caffeine consumption.



Aside from keeping you awake when you are sleep deprived, caffeine has been shown to enhance some cognitive performances such as attention, vigilance, and reaction time 2. When it comes to physical performance, studies have shown impacts of reducing effort perception and lowering pain sensations when caffeine is consumed before an activity2. For both cognitive and physical performance, moderate doses can be suggested for optimal results2. A moderate amount of caffeine is about 100 to 200 mg a day, which is around one to two 5-ounce cups of coffee3. When this drug/food additive is consumed, its effect is based on the concentration. The concentration of caffeine can vary depending on the type of food or beverage.



Energy drinks are the most common beverage consumed that contain caffeine among adolescents. Some drinks have a range of 50-505 mg of caffeine in each bottle or can5. Dependence and withdrawal has become very prominent in many children and adolescents with the most common side effect of headaches5. Other side effects can include fatigue, drowsiness, dysphoric mood, difficulty concentrating, depression, irritability, nausea, and muscle aches or stiffness. Caffeine is not as addictive as other types of stimulating drugs, but it can cause mild physical dependence which, just like any other drug, will lead to withdrawal when stopped suddenly6. It triggers some of the same neurotransmitters that are associated with other stimulant drugs. There are many foods and beverages that contain different doses of caffeine nowadays so it is hard to get away from it. Caffeine’s effects on the body are influenced by: age, sex, weight, height and many other factors. This isn’t going to tell you that caffeine is good or bad for you, but are you still going to drink that extra cup of coffee?




Each of these Contain 400 mg of Caffeine



           2- 5oz cups of coffee                                                            

                11 Cans of Coca-Cola

  5.5 Shots of Espresso

  2.5 Cans of Monster     





The information provided is intended for factual purposes only, not to suggest or provide medical advice to you, the reader. Consult a medical professional with further questions or concerns regarding the information listed.





Neurotransmitter: (noun) a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure.

Diuretic: (adjective) causing increased passing of urine.

Dysphoric: (noun) uneasy about life or similar to the feeling of anxiety type of





(1) Andrews, R. All About Caffeine. PrecisionNutrition: 2017

(2) McLellan, TM., Caldwell, JA., & Lieberman, HR. A review of caffeine's effects on cognitive, physical and occupational performance. Neuroscience and Biobehavioral Reviews 2016;71: 294-312.

(3) FDA. Medicines in my Home: Caffeine and Your Body. FDA: Food and Drug Administration: 2007.

(4) MedlinePlus. Caffeine. U.S. National Library of Medicine: February 23 2017.

(5) Reissig, CR., Strain, EC., & Griffiths, RR. Caffeinated energy drinks--- A growing problem. Drug and Alcohol Dependence. 2009;99:1-10.

(6) WebMD. Caffeine Myths and Facts.WebMD: 2005-2017.





About the Author







Casey Wayrynen is a second year Franklin Pierce student majoring in Health Sciences. Wayrynen grew up not far from Rindge, New Hampshire, so she commutes. She plans to pursue a career in Diagnostic Medical Sonography which entails a 2-year training program after her 4 years here at FPU.

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