The Effects of Consuming Caffeine & Energy Drinks on a Long Shift

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Content provided by JEMS.

By Elizabeth Smith, EMT-B

Most of us know at least one person who refuses to speak or function in the morning until they’ve had their first cup of coffee. Actually, chances are you know several, since a reported 90% of North Americans consume caffeine on a daily basis.1 EMS providers are likely no exception, since long hours, switching between days and nights, and busy shifts with no sleep can put extra stress on our bodies and cause extreme fatigue.

Many providers are turning to the wide variety of energy-boosting products now available: the old standard of coffee, increasingly popular energy drinks and energy shots, and even foods supplemented with caffeine including gum and candy. With all of these available options, you may find yourself wondering: What is safe, how much is too much, and what is the best way to fight off fatigue?

The most basic element in all “energy” products is caffeine. Caffeine has been proven to improve alertness, reaction time and mood. It works in the brain as an adenosine inhibitor—adenosine promotes sleep, and caffeine and adenosine fit into the same receptor. When caffeine molecules occupy the receptor, adenosine can’t lock in, so the body is not prompted to feel tired.1

In large doses, however, caffeine can have negative effects ranging from headaches to elevated blood pressure and cardiac arrhythmias. True caffeine overdose is possible but unlikely and generally involves taking medications containing caffeine.1

The Food and Drug Administration (FDA) recommends consuming no more than 600mg of caffeine daily.2 The table on p. 51 shows the amount of caffeine contained in various common beverages. Based on the FDA guideline for caffeine alone, a coffee drinker, for example, should consume no more than 36 oz. of coffee per day. Some studies have shown, however, that caffeine-sensitive individuals can experience side effects including headaches, anxiety and nausea from as little as 400 mg per day, so it’s important to be aware of your own body and your reaction to stimulants.1

Apart from caffeine, energy drinks tout additives such as taurine and B-vitamins as part of the “energy blend.” 5-Hour Energy boasts 8,333% of the daily value of B12. While B12 is important in the physiological process of energy metabolism, this isn’t a situation where more is better. The vast majority of people get more than enough B12 from their daily diets. The only individuals likely to be deficient in B12 are strict vegetarians and people with specific medical conditions that reduce B12 absorption (decreased stomach acidity, pernicious anemia, celiac disease, Crohn’s disease, previous gastric surgery, etc.).3 However, the excessive amount of B12 should not be harmful to a healthy person. B-vitamins are water soluble and excreted as waste, so essentially this high dose gives you very expensive urine.

Guarana is another common ingredient in energy drinks, and is best known for its high caffeine concentration. Taurine, another frequent additive, is similarly common in the standard diet. It’s found naturally in meat and fish. Some research has shown that it may help with athletic performance or mental ability, but more research is needed to show a definite benefit.4

Isolated reports of cardiac arrest, liver failure or other serious health issues surface from time to time with energy drinks reported to be the cause. The FDA investigates these adverse events, and collected data are available to the public.5 No definite link has yet been found.

As with all dietary supplements, it’s a good idea to discuss energy drinks with your personal health professional before beginning use to see if they’re contraindicated with your medical conditions or current medications. Be sure to discuss all sources of caffeine you’re taking—mixing and matching energy drinks, coffee and caffeine-supplemented foods can quickly add up to an excessive caffeine jolt.

If you’re not interested in pumping up on artificial pep, a tried and true way to increase energy is to revamp your diet. Eating breakfast every day starts your body off on the right foot. Choose a meal that’s a mixture ofcarbohydrates, protein and fat. Carbohydrates provide energy, protein helps keep endurance high, and fat makes you feel full.

Throughout the day choose meals that are a mixture of these nutrients, and to avoid a sugar high followed by a sugar crash, choose complex carbohydrates (whole grains—wheat bread, brown rice, etc.) instead of refined sugars like those found in candy and sodas. Complex carbohydrates break down more slowly, allowing your blood sugar level to rise and fall more gradually than simple sugars which are absorbed very rapidly.

Examples of ambulance-friendly snacks that fit the bill: half a whole-grain bagel with peanut butter and an apple; a hard-boiled egg with a whole-wheat pita; low-fat cheese and whole-grain crackers (storing the cold items in a cooler, of course). Try to eat every three to four hours, even if it’s just a piece of fruit or a granola bar, to keep your blood sugar stable and your metabolism running strong. This is especially true if you have diabetes.

A few other easy ways to keep up your energy level:

>> Stay hydrated! Drink enough water to avoid the draining effects of running dry. Remember that the average person needs about 30 mL water per kg body weight every day.

>> Take a quick walk. Even a few laps around the station or down the hall at the hospital can be enough to get your blood pumping and give you a second wind.

>> Try to keep your sleep schedule standard. It’s difficult when you bounce back and forth between shifts, but if you can, try to follow your work schedule on your days off to keep your rhythms regular.

>> Get good sleep. Try to avoid sleeping with the television on in the background. Even if you’re only able to grab a few minutes between calls, make an effort to relax in a dark, quiet room to get the most out of your rest.


1. Heckman MA, Weil J, Gonzalez de Mejia E. Caffeine (1, 3, 7-trimethylxanthine) in foods: A comprehensive review on consumption, functionality, safety, and regulatory matters. J Food Sci. 2010;75(3):R77–R87.

2. Food and Drug Administration. (2007.) Medicines in my home: Caffeine and your body. Retrieved Oct. 28, 2013, from…

3. NIH Office of Dietary Supplements. (June 24, 2011.) Dietary supplement fact sheet: Vitamin B12. Retrieved Oct. 28, 2013, from

4. Zeratsky K. (March 27, 2012.) Taurine in energy drinks. Mayo Clinic. Retrieved Oct. 28, 2013,

5. U.S. Department of Health and Human Services. (n.d.) Voluntary and mandatory reports on 5-Hour Energy, Monster Energy, and Rockstar Energy Drink. Food and Drug Administration. Retrieved Oct. 28, 2013, from


Caffeine quantities in common beverages

(and Standard Serving)


Decaf coffee (8oz)


Plain coffee (8oz)


Espresso (2oz shot)


Hot Tea (8oz)


Green Tea (8oz)


Coca Cola (12oz can)


Pepsi (12oz can)


Mountain Dew (12oz can)


Red Bull (8.4oz can)


Rockstar (16oz can)


Monster (16oz can)


5-Hour Energy (1.93oz shot)


Caffeine has been proven to improve alertness, reaction time and mood. In large doses, however, caffeine can have negative effects ranging from headaches to elevated blood pressure and cardiac arrhythmias.