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On average, adults in the U.S. consume between 110-260 mg of caffeine per day – substantially less than 400 mg per day, which is the upper limit of moderate consumption.

Source: U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at

Caffeine and Academic Performance

Research suggests that drinking caffeinated beverages promotes mental alertness. This effect is one of the most common reasons cited for caffeine use.

Be careful not to consume too much caffeine, which can cause insomnia, nervousness, restlessness and a rapid heartbeat. ASU students surveyed report that sleep difficulties and anxiety are two of the top five barriers to academic performance. Stop caffeine use in the early afternoon to promote healthy sleep. If you get anxious or jittery with caffeine, this may actually be working against your best interests.


What is it and how much is safe?

Caffeine is a bitter substance found in coffee, tea, soft drinks, energy drinks, chocolate, kola nuts and certain medicines. It has many effects on the body's metabolism, including stimulating the central nervous system. This can make you more alert and give you a boost of energy. Caffeine is one of the most widely used stimulants, and is generally considered safe at moderate levels of use: 300-400 mg of caffeine per day, or the amount in 3-4 cups of coffee.

As with most foods that don't contain essential nutrients, the key to caffeine intake is moderation.

Source: U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at .

Caffeine is also found in prescription and over-the-counter medicines where it is used to treat tiredness or drowsiness and to improve the effect of some pain relievers. The US Food and Drug Administration advises consumers avoid pure powdered caffeine, as this form of caffeine increases the chance of consuming a lethal dose. A single teaspoon of powdered caffeine is roughly equivalent to 28 cups of coffee.

Source:  US Food and Drug Administration.  Products and Ingredients: Pure and highly concentrated caffeine.  Retrieved from

Caffeine is a diuretic

Caffeine is a diuretic. Research suggests that the diuretic action of caffeine is most relevant for those who do not regularly use caffeine. For people who have developed a tolerance to caffeine, its diuretic qualities are diminished, as are some of the other effects of caffeine. Doses of caffeine equivalent to the amount found in a typical cup of coffee or tea have limited diuretic activity.

Source: Maughan, R.J., Griffin, J. (2003) Caffeine ingestion and fluid balance: a review. Journal of Human Nutrition and Diet. Dec. 16 (6).

Got Sleep Deprivation?

The CDC says that students who are working or studying long hours may experience episodes of sleep deprivation. This can cause daytime sleepiness, sluggishness, and difficulty concentrating or making decisions. Teens and young adults who do not get enough sleep are at risk for problems, such as automobile crashes; poor grades and school performance; depressed moods; and problems with friends, fellow students and adult relationships.

You may think that if you can't sleep at night, you can just make up for it by drinking caffeine throughout the day.  This is a common misconception. Drinking caffeine throughout the day could be what's causing your insomnia!

Side Effects

Too much caffeine can cause unpleasant side effects:

  • Insomnia
  • Anxiety
  • Nervousness
  • Digestive problems
  • Rapid heartbeat
  • Irritability
  • Muscle tremors

Caffeine intoxication

While many drinks and products containing caffeine have levels below the range that would have negative effects for most people, energy drinks can provide a wide range of caffeine in each drink. One energy drink may have 75 mgs of caffeine, which is the amount in a cup of coffee. Another may have 500 mgs of caffeine, which could put someone who hasn't built up a tolerance to caffeine into caffeine intoxication, resulting in nervousness, anxiety, restlessness, insomnia, nausea, vomiting, tremors and rapid heart rate.

Mixing alcohol and energy drinks

The Food and Drug Administration (FDA) reports that although there is little research on the effects of mixing caffeine and alcohol, several studies have suggested that people get more intoxicated and engage in riskier behavior when they drink the combination beverages than when they drink alcohol alone. Caffeine masks the effects of alcohol, tricking users into believing they can keep drinking well past the point of drunkenness. In November 2010, the FDA required several manufacturers of caffeinated alcoholic beverages to remove their products from the market.

Tolerance and Withdrawal

When people use caffeine every day, their bodies get used to it and they develop a tolerance. Some studies show that caffeine causes a physical dependence or addiction. If a person gets withdrawal symptoms when they suddenly stop using caffeine, then the person has a physical dependence on caffeine. Withdrawal symptoms can include: severe headaches, muscle aches, temporary feelings of depression and irritability.


Keep a record of your caffeine intake and any side effects. Use the table below to track the amount of caffeine you consume, and record this number as well as the following on a page in your journal or notebook:

  • Rapid- racing heartrate
  • Jitters
  • Alertness
  • Insomnia – unable to fall or stay asleep
  • Nervousness or anxiety
  • Upset stomach
  • Irritable mood
  • Irritability
  • Headaches
  • Muscle tremors
  • Other

Every caffeinated product has different caffeine content. Here are some examples:

Caffeinated Beverages Caffeine (mg) Ounces
Coffee 77-150 6
Tea 40-80 5
Coca-Cola 34.5 12
Dr. Pepper 41 12
Mountain Dew 54 12
Pepsi-Cola 38 12



Energy Drinks Caffeine (mg) Can Size (oz)
Amp 75 8.4
Red Bull 80 8.4
Monster and NOS 160 16
Rockstar 160 16
Wired X505 505 24



Caffeine Pills 100-300 (mg) 1 pill


If you decide to cut back on caffeine, try this:

  • Cut your caffeine intake in half by mixing decaf and regular
  • Substitute coffee with decaffeinated and herbal teas
  • Eliminate other sources of caffeine from your diet, such as sodas, energy drinks, cocoa and some cold medicines (check ingredient labels)
  • Remember to give caffeine 8 hours to wear off completely for a good night’s sleep.

Use Natural Energizers

  • Have a good sleeping environment and develop a consistent sleep routine.
  • Get up and move. Physical activity in the moment can help energize you when studying. Walk, stretch, run in place, do jumping jacks or push-ups. Any movement will be of benefit to regain energy.
  • Talk with someone about something you have a strong interest in. Sometimes just a few minutes talking or a shift of focus can help you to regain focus on the task at hand.
  • What you eat can make you sleepy or energize you. Avoid carbohydrate rich foods like pasta and rice, which can send you to nap-land.
  • On the other hand, eat snacks that have a healthy balance of carbohydrates, protein and fat—the energy nutrients. For example: Apples with peanut butter, yogurt with strawberries and granola, mixed nuts with dried fruit.
  • Take a relaxation or meditation break. It is amazing how energized you can feel when you have taken the time to relax.
  • Stress can be a huge energy drain. Learn to manage stress in positive ways to regain energy.


Learn more about caffeine please use the following resources:

Find help and support please use the following resources:

ASU, Counseling Services ( offers confidential time-limited professional counseling and crisis services for students. For after hours or weekends EMPACT’s 24 hour ASU-dedicated crisis hotline can be reached at 480-921-1006

ASU, Recovery Rising, Collegiate Recovery Program ( Aims to connect students in recovery, interested in recovery, or want to support someone in recovery through events, open round table discussions, and campus AA meetings.