thesis statement for caffeine addiction

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Caffeine Addiction Symptoms and Withdrawal

Daniel B. Block, MD, is an award-winning, board-certified psychiatrist who operates a private practice in Pennsylvania.

What Is Caffeine Addiction?

• Caffeine Adverse Effects
• Caffeine Withdrawal
• Other Similar Disorders
• Are You Addicted to Caffeine?
• How to Cope

Caffeine addiction is the excessive and harmful use of caffeine over a period of time, such that it has negative effects on your health, social interactions, or other areas of your life.

Coffee and other caffeinated products can create a physical dependence, leading to chemical changes in the brain. Daily consumption can quickly lead to a caffeine addiction, characterized by cravings and withdrawal symptoms if intake is reduced or ceased.

According to the Centers for Disease Control and Prevention (CDC), approximately 80% of Americans consume caffeine daily.

To be clear, caffeine has been associated with many positive side effects. Research has connected this plant-derived stimulant to improved mood , relief from headaches , and perhaps a reduced risk of other major medical issues such as strokes , Parkinson's, and Alzheimer's . Large studies that tracked people over time found that coffee drinkers were less likely to die during follow-up.

Yet, some people experience negative issues due to caffeine use or have difficulty coping without caffeine. Though rare, there have even been cases of caffeine overdose.

Caffeine affects the brain's reward system, which triggers the release of a chemical called dopamine. Dopamine causes people to feel good, creating a reward cycle that motivates them to keep consuming it and experiencing that same level of reinforcement.

It also causes physiological dependence, which means that when you reduce or stop your caffeine intake, you will likely experience withdrawal symptoms like tiredness, headaches, and irritability .

When you have a caffeine addiction, it means that your caffeine use negatively disrupts your life, yet you're unable to stop consuming it. Or you consume it in amounts that are potentially dangerous to your health despite knowing that it may harm you mentally or physically.

Caffeine is the most widely used drug worldwide. Coffee and soda are the top caffeine sources in the United States, whereas African and Asian countries consume them in soda and tea . Caffeine is also present in many common foods (almost anything with chocolate ), making it easy to over-consume.

While caffeinated products like coffee, soda, and energy drinks are less reinforcing than other addictive substances, that does not mean they don't have potential adverse health effects.

Symptoms of Caffeine Addiction

Although caffeine addiction is not a formally recognized condition in the " Diagnostic and Statistical Manual of Mental Disorders (DSM-5) ," a manual used by clinicians to classify and diagnose mental health concerns, the publication mentions some caffeine-related issues, such as intoxication and withdrawal.

Caffeine intoxication, caffeine withdrawal, caffeine-induced anxiety disorder, and caffeine-induced sleep disorder are all recognized in the "DSM-5," and caffeine use disorder has been identified as requiring further study.

As caffeine is a stimulant, consuming too much can cause a cluster of symptoms associated with brain and nervous system stimulation. These symptoms include:

• Feeling shaky
• Increased blood pressure
• Nervousness
• Racing heart, or other heartbeat abnormalities
• Sleep issues

This type of addiction can even overlap with work addiction , as some people use the stimulating effects of this substance to perform better at their job mentally and/or physically.

As with all addictions, the pleasurable effects of caffeine can also sometimes mask other issues. Lack of energy and depression may underlie caffeine addiction. People may rely on caffeine to compensate for sleep disorders.

How Caffeine Can Negatively Affect Your Health

Caffeine has various effects on the body that are potentially harmful to your health. Caffeine has been associated with increased blood pressure and heart rhythm changes.

Some caffeinated products, such as coffee and soda, can cause gastrointestinal disturbances.

There is also a question of whether caffeine might increase your risk of osteoporosis. One study found this to be the case for women in menopause with high caffeine intake.

Caffeine can also decrease your health by disturbing your sleep if consumed within six hours of bedtime.

When you are sleep deprived, it makes it harder to function efficiently during the day. Sleep is also when your body heals, making it essential for total health and immune function.

Excessive caffeine intake can also have an impact on mental health. Increased anxiety can occur, particularly in those sensitive to caffeine's effects or who have a previously existing anxiety disorder. 

Some research has shown that caffeine may be linked to symptoms of psychosis and mania in people who have psychotic disorders or mood conditions.

Symptoms of Caffeine Withdrawal

Just as taking in too much caffeine can present issues, so can suddenly removing it from your diet. This can result in caffeine withdrawal , which produces symptoms that are the opposite of consuming too much. This effect can be especially profound in people who are addicted to caffeine.

The symptom most often noticed by people going through caffeine withdrawal is a headache, which may range from mild to severe.

Other symptoms associated with trying to cut back your caffeine habit or missing your daily "dose" are:

• Feeling tired or sleepy
• Reduced mental alertness
• Slower reaction times
• Worsened performance on memory tasks

Occasionally, people withdrawing from caffeine also experience flu-like symptoms, such as nausea as well as mood changes.

How Long Does Caffeine Withdrawal Last?

Symptoms of caffeine withdrawal typically start around 12 to 24 hours after your last caffeine dose. You may experience these symptoms for between two to nine days.

7 Quick Tips to Help with Caffeine Withdrawal

Caffeine addiction and other conditions.

The stimulating effects of caffeine can sometimes cause physical symptoms and behaviors that look and feel like—and therefore be easily confused with—other disorders. Therefore, it is important to let your doctor or mental health clinicians know how much caffeine you are consuming if you are being assessed for any condition.

Anxiety Disorders

For example, caffeine intoxication produces symptoms that can easily be confused with anxiety disorders , such as panic attacks. Too much caffeine can also worsen symptoms of these disorders by intensifying feelings of worry, causing racing thoughts, increasing heart rate, and preventing relaxation and good-quality sleep.

Other Conditions

People who are overstimulated with caffeine can also exhibit symptoms consistent with attention deficit disorders . Conversely, caffeine withdrawal shares similar symptoms with mood disorders . Other health concerns that can be confused with caffeine intoxication include:

• Manic episodes
• Panic disorder
• Generalized anxiety disorder
• Sleep disorders
• Migraine and other headaches
• Viral illnesses
• Sinus conditions
• Medication-induced side effects, such as akathisia or an inability to stay still

Substance Use

It can also be mistaken for and worsen symptoms of withdrawal from other substances, such as amphetamines  and cocaine . Stimulant drugs such as these are often cut with caffeine, increasing the likelihood that caffeine withdrawal is involved in withdrawal from these drugs.

Caffeine Can Induce Other Disorders

Some disorders are triggered by the use of caffeine. Examples of these types of disorders include caffeine-induced anxiety disorder and caffeine-induced sleep disorder.

Do You Have a Caffeine Addiction?

If you suspect that you are addicted to caffeine, such as if you have a coffee addiction, it is essential to take stock of your situation. Assessing your intake, the impact, and how you feel can help you better determine if you need to cut back.

Addiction involves excessive use of caffeine and relying on this stimulant to better cope with life despite any adverse effects you may be experiencing. To figure out whether you might be addicted, it helps to:

Assess Your Intake

Calculate how much caffeine you are consuming on a typical day. Remember that gourmet espresso, lattes, and cappuccino typically contain more caffeine than regular drip or instant coffee, soda, and other common caffeine-containing foods and drinks. Therefore, this should be accounted for when determining your normal intake.

Pay Attention to How You Feel

Make a note of any side effects you experience after consuming caffeine. Also, note any adverse effects you feel if you lower your normal intake or skip caffeine entirely. Pay attention to both mental and physical effects for a more complete picture of how you are impacted by its use.

Consider How Caffeine Affects Your Life

Think about your caffeine habit and how it affects your life as a whole. Do your relationships suffer if you don't get your morning coffee, for instance? Could your caffeine intake be contributing to your work anxiety ?

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database .

Coping With a Caffeine Addiction

Caffeine addiction is so common that we don't even notice it most of the time. But when you can greatly reduce or quit caffeine to reduce the adverse effects it is having on you, you may find it easier to get back in touch with your own natural energy and can relax when night falls.

If you consume more caffeine than is healthy, you can reduce your caffeine intake or cut it out completely.

If your responses to caffeine (or a lack of caffeine) affect you negatively, speak to your healthcare provider. Similarly, if you have another health condition that might be impacted by caffeine use, such as heart disease, or even if you are pregnant or breastfeeding, discuss options with your doctor immediately.

Make a Plan to Cut Back or Quit

The vicious cycle of addiction is often the same with caffeine as with other addictive substances. As the effects of the caffeine begin to wear off, you might feel a crash in energy and that you can't keep going without another boost. Your doctor can help you move past this without giving in.

Gradually Lower Your Caffeine Intake

Since stopping "cold turkey" can make you feel worse, most people need to reduce caffeine intake gradually rather than abruptly. Your doctor can help you devise a suitable plan based on your typical caffeine consumption. This can help reduce or eliminate any withdrawal effects.

How to Taper Your Caffeine Dose

Instead of cutting your caffeine intake abruptly, try reducing your regular intake by about 10% every two weeks. One way to do this is to reduce the strength of your caffeinated drinks by diluting them with a decaffeinated version.

Find Ways to Manage Withdrawal Symptoms

Withdrawal symptoms such as headache and fatigue may leave you wanting to reach for a cup of coffee or a can of soda, so finding ways to cope with these symptoms is essential. Consider using over-the-counter pain medications like Tylenol or ibuprofen to relieve headache symptoms. Other strategies that can help include:

• Getting enough sleep
• Drinking plenty of water
• Finding ways to stay busy
• Engaging in physical exercise to boost energy levels

Seek Help for Mental Health Symptoms

If you feel you are using caffeine to cope with an emotional problem, such as depression or anxiety , talk to your physician about treatment options. The right treatment could make a huge difference for you.

Caffeine addiction often overlaps with other behavioral addictions, such as sugar addiction . So, you might find that evaluating your caffeine intake also identifies other behaviors that need to be addressed.

Caffeine is a stimulant often consumed daily in many forms, including coffee, soda, tea, energy drinks, and chocolate. Low or moderate amounts are safe and may even have certain health benefits. Excessive intake, however, can adversely affect health and lead to caffeine addiction.

If you think you have a coffee addiction or that you are consuming too much caffeine, gradually lowering your intake can help you get control of your caffeine habit. 

Centers for Disease Control and Prevention. Caffeine and long work hours .

Nehlig A. Effects of coffee/caffeine on brain health and disease: What should I tell my patients? Pract Neurol . 2016;16(2):89-95. doi:10.1136/practneurol-2015-001162

Freedman N, Park Y, Abnet C, Hollenbeck A, Sinha R. Association of coffee drinking with total and cause-specific mortalitiy . N Engl J Med . 2012;366(20):1891-1904. doi:10.1056/NEJMoa1112010

Reyes C, Cornelis M. Caffeine in the diet: Country-level consumption and guidelines . Nutrients . 2018;10(11):1772. doi:10.3390/nu10111772

Addicott MA. Caffeine use disorder: A review of the evidence and future implications .  Curr Addict Rep . 2014;1(3):186-192. doi:10.1007/s40429-014-0024-9

Sweeney MM, Weaver DC, Vincent KB, Arria AM, Griffiths RR. Prevalence and correlates of caffeine use disorder symptoms among a united states sample . Journal of Caffeine and Adenosine Research . 2020;10(1):4-11. doi:10.1089/caff.2019.0020

Bodar V, Chen J, Gaziano JM, Albert C, Djoussé L. Coffee consumption and risk of atrial fibrillation in the Physicians' Health Study . J Am Heart Assoc . 2019;8(15):e011346. doi:10.1161/JAHA.118.011346

Temple JL, Bernard C, Lipshultz SE, Czachor JD, Westphal JA, Mestre MA. The safety of ingested caffeine: A comprehensive review .  Front Psychiatry . 2017;8:80. doi:10.3389/fpsyt.2017.00080

Costa A, Neto da Silva M, Brito L, et al. Osteoporosis in primary care: An opportunity to approach risk factors . Braz J Rheumat . 2016;56(2):111-116. doi:10.1016/j.rbre.2015.07.014

Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed . J Clin Sleep Med . 2013;9(11). doi:10.5664/jcsm.3170

Wang HR, Woo YS, Bahk WM. Caffeine-induced psychiatric manifestations: a review .  Int Clin Psychopharmacol . 2015;30(4):179-182. doi:10.1097/YIC.0000000000000076

Rogers P, Heatherley S, Mullings E, Smith J. Faster but not smarter: Effects of caffeine and caffeine withdrawal on alertness and performance . Psychopharmacology . 2012;226:229-240. doi:10.1007/s00213-012-2889-4

Juliano L, Huntley E, Harrell P, Westerman A. Development of the caffeine withdrawal symptom questionnaire: Caffeine withdrawal symptoms cluster into 7 factors . Drug and Alc Depend . 2012;124(3):229-234. doi:10.1016/j.drugalchdep.2012.01.009

Lin YS, Weibel J, Landolt HP, et al. Time to recover from daily caffeine intake .  Front Nutr . 2022;8:787225. doi:10.3389/fnut.2021.787225

Pohler H. Caffeine intoxication and addiction .  J Nurse Pract . 2010;6(1):49-52. doi:10.1016/j.nurpra.2009.08.019

National Institute of Mental Health. Depression basics .

By Elizabeth Hartney, BSc, MSc, MA, PhD Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada.  

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Caffeine Addiction: How Much Is Too Much?

Anxiety, fatigue, and general uneasiness may be signs it’s time to cut back

• Addiction Symptoms
• Withdrawal Symptoms
• Addiction Quantity
• Drinking Less Caffeine

Caffeine dependence and addiction are caffeine use disorders, as defined in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), the handbook used by healthcare providers to diagnose mental disorders. These terms are used interchangeably, though researchers prefer the term "dependence" because it is used most frequently in published literature.

This article explains caffeine addiction and withdrawal symptoms, how much caffeine can cause dependence, and how to drink less caffeine.

fcafotodigital / Getty Images

Symptoms That Suggest Caffeine Addiction

So, is caffeine an actual addiction? The short answer is, yes, it can be.

"Addiction," in general, is an older term that has more recently been updated in favor of more accurate phrasing: substance use disorder . People with substance use disorders do not control their substance use despite harmful consequences. In the case of caffeine, consequences may include anxiety, insomnia, and nausea.

According to the DSM-5, caffeine use disorder is defined as "a problematic pattern of caffeine use leading to clinically significant impairment or distress." For diagnosis, this must be accompanied by the first three symptoms on the following list and may have the symptoms listed after those:

• Persistent desire or unsuccessful attempts to reduce or control caffeine use
• Continued caffeine use despite knowing it results in physical or psychological problems
• Withdrawal symptoms when not using
• Ingesting larger amounts or over a longer period than intended
• Recurrent caffeine use that results in interference with work, school, or home responsibilities
• Continued caffeine use despite social or interpersonal problems
• Tolerance (needing increased amounts of caffeine)
• Spending a great deal of time trying to obtain caffeine or recover from its effects
• Craving caffeine

Caffeine Sensitivity, Dependence, and Withdrawal

Caffeine sensitivity describes how strongly a person reacts to caffeine. If you have low sensitivity, you may need to drink more caffeine to feel the desired effects. However, if you have high sensitivity, you may feel effects more quickly, including unwanted side effects like nervousness.

Caffeine dependence means your body requires caffeine each day. You may have trouble focusing without it, have trouble not using it, or experience withdrawal when you can't have it.

Caffeine withdrawal is a group of symptoms that accompany not having caffeine. These commonly include headaches and drowsiness.

Caffeine Withdrawal Symptoms

If your body depends on caffeine, you may experience withdrawal symptoms when you don't have it. Caffeine withdrawal symptoms commonly include the following:

• Irritability
• Depressed mood
• Difficulty concentrating
• Flu-like symptoms

Caffeine withdrawal symptoms can start as soon as 12 to 24 hours after stopping caffeine and last up to a little over a week.

Caffeine Quantity: How Much Makes You Addicted?

How much caffeine do you have to drink a day to be considered addicted? Since everyone's sensitivity is different, there isn't an exact number for how much caffeine is too much . Plus, factors like body weight and medications can influence how caffeine affects a person.

Instead of a specific quantity, caffeine addiction or dependence is marked by behaviors and increasing tolerance to caffeine. In other words, needing to consume larger amounts than you did in the past for the same effect means your tolerance has increased. Increasing tolerance is one of the key symptoms of caffeine use disorder.

The Food and Drug Administration (FDA) has set the upper limit for most healthy adults at 400 milligrams (mg) daily—around four cups of coffee.

People who are pregnant or breastfeeding should consume far less. Experts recommend no more than 200 mg daily while pregnant, while capping caffeine at 300 mg daily during lactation.

Beverages With Higher Caffeine Content

Some drinks have excessive amounts of caffeine. Consuming these, especially regularly, could make your tolerance higher and withdrawal symptoms worse. Examples of high-caffeine drinks include energy drinks (or concentrated drops) and espresso.

Highly concentrated caffeine, like pure powdered or liquid concentrate caffeine, can also be dangerous. According to the FDA, just 1 teaspoon of pure powdered caffeine can contain as much caffeine as 28 cups of coffee, while 4 ounces of liquid, highly concentrated caffeine contains as much as 20 cups. These levels are toxic and dangerous.

How to Drink Less Caffeine

If you are looking for strategies to reduce caffeine use, it's best to cut back gradually. Researchers recommend tapering down over a period of four to six weeks. Doing so will help your body adjust to the reduced levels over time and lessen the chances of experiencing withdrawal symptoms.

In one study, participants who used a gradual tapering-off method reduced their caffeine consumption as follows, based on their usual caffeine intake before starting the reduction:

• Week 1: Consume 75% of usual daily caffeine intake.
• Week 2: Consume 50% of usual caffeine intake.
• Week 3: Consume 25% of usual caffeine intake.
• Week 4: Consume 12.5% of usual caffeine intake.
• Week 5: Consume less than 50 mg of caffeine per day.

You could modify the above guidelines depending on your goals to suit your needs.

Alternative Drinks With Less Caffeine

As you work to reduce your caffeine consumption, replacing your typical coffee or soda with another drink can help. Here are some other lower-caffeine alternatives to try:

• Mushroom coffee
• Sparkling water
• Lemon water

Adjusting to a different drink can take time. That's why tapering your coffee intake while slowly substituting some of your caffeine with other low- or no-caffeine beverages can help.

Caffeine addiction or dependence is called caffeine use disorder. If you have trouble stopping drinking caffeine, you keep using it even though it causes problems, or you have withdrawal symptoms, you may have caffeine dependence.

Gradually reducing how much caffeine you consume may help limit the likelihood of experiencing withdrawal symptoms.

Meredith SE, Juliano LM, Hughes JR, Griffiths RR. Caffeine use disorder: a comprehensive review and research agenda .  J Caffeine Res . 2013;3(3):114-130. doi:10.1089/jcr.2013.0016

American Psychiatric Association. What is a substance use disorder? .

Sweeney MM, Weaver DC, Vincent KB, Arria AM, Griffiths RR. Prevalence and correlates of caffeine use disorder symptoms among a United States sample .  J Caffeine Adenosine Res . 2020;10(1):4-11. doi:10.1089/caff.2019.0020

Rodda S, Booth N, McKean J, Chung A, Park JJ, Ware P. Mechanisms for the reduction of caffeine consumption: what, how and why .  Drug Alcohol Depend . 2020;212:108024. doi:10.1016/j.drugalcdep.2020.108024

Food and Drug Administration. Spilling the beans: how much caffeine is too much?

Centers for Disease Control and Prevention. Maternal diet .

American College of Obstetricians and Gynecologists. How much coffee can I drink while pregnant? .

Food and Drug Administration. Pure and highly concentrated caffeine .

Evatt DP, Juliano LM, Griffiths RR. A brief manualized treatment for problematic caffeine use: a randomized control trial .  J Consult Clin Psychol . 2016;84(2):113-121. doi:10.1037/ccp0000064

By Kathi Valeii As a freelance writer, Kathi has experience writing both reported features and essays for national publications on the topics of healthcare, advocacy, and education. The bulk of her work centers on parenting, education, health, and social justice.  

• Undergraduate Honors Thesis

The Effects of Caffeine on Sleep Following Sleep Deprivation Public Deposited

• Introduction: In modern day society, pressures from the business and academic worlds cause people to consistently self-impose sleep restriction in order to meet deadlines. To maintain a level of alertness during these periods, many individuals rely upon caffeinated beverages in order to heighten their awareness and repress their drive for sleep. However, caffeine’s wakefulness promoting properties can negatively affect sleep quality during the following night’s sleep, resulting in an individual feeling less rested upon awakening. This thesis looked at the combined effects of sleep deprivation and caffeine on daytime recovery sleep. The study design mimics staying up all night in order to meet societal demands (e.g. tests, deadlines) and thus is directly translatable to common society. Methods: Thirty drug free males and females ages 18 to 35 participated in this study. Subjects completed an in-laboratory study. Subjects were given an 8 h baseline polysomnographically recorded sleep opportunity on the first night. Following the baseline night, subjects were sleep deprived for 28 h. Ten subjects were assigned to a caffeine group and administered a caffeine pill at 23 h awake. A 5 h recovery sleep opportunity followed the sleep deprivation episode. Sleep records were visually scored and compared within subjects and between conditions. Results: Sleep deprivation significantly decreased amounts of stage 2, REM and REM latency during recovery sleep in both the caffeine and placebo groups. Caffeine, in combination with sleep deprivation, significantly increased the amount of wakefulness and decreased the amount of stage 3/4 sleep when compared to placebo. These effects were seen when comparing the entire sleep episodes as well as when comparing the first 300 minutes of each sleep episode. Conclusion: The effect of caffeine attenuates the ability to dissipate the homeostatic build-up of sleep pressure that results from extended wakefulness. This is seen as a significant interaction between caffeine and sleep deprivation in the amount of deep sleep present in the recovery sleep episode. We also see a significant increase in the percent wakefulness in the caffeine group when compared to placebo indicate that caffeine 5 hours prior to daytime recovery sleep disturbs sleep even when sleep pressure is high. The disturbed sleep findings have important implications for individuals who use caffeine to promote wakefulness at night. Support: NIH R01 HL081761
• Smith, Benjamin
• Integrative Physiology
• Jr., Kenneth P. Wright
• University of Colorado Boulder
• In Copyright
• English [eng]

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65 Caffeine Essay Topic Ideas & Examples

🏆 best caffeine topic ideas & essay examples, ⭐ good research topics about caffeine, 👍 simple & easy caffeine essay titles.

• Negative Effects of Caffeine and Energy Drinks It leads to avoidance of making choices and biasness and may result in impaired self-regulation that may affect the social problems of the users.
• Starbucks and Caffeine: Is It Unhealthy? It is the caffeine in coffee which makes it addictive, so addictive in fact that it’s the most addictive substance known to mankind. We will write a custom essay specifically for you by our professional experts 808 writers online Learn More
• The Caffeine Effect on Students’ Test Performance Thus, the critical interest in this experiment is to determine the relationship between coffee consumption before exams and students’ own performance on those exams.
• Caffeine Addiction as a Mental Disorder And it is a rather pragmatic question stipulated by the professionals need to debate about, but not by the addiction nature itself.
• The Impact of Caffeine on Athletic Performance Caffeine is a legal substance, so it may be used to enhance athletic performance within the bounds of the law. The amount of anhydrous caffeine given to study participants is an independent variable.
• Critique: “Spilling the Beans: How Much Caffeine Is Too Much?” The third was the most specific and supported paragraph about the specifics of the European country’s culture and habits regarding coffee.
• Caffeine: Health Benefits and Risks The topic I want to address today is on health effects of caffeine. It is mostly found in seeds of the Coffea plant, and the safe dose is determined to be 400 mg/day.
• Restrictions, Warning Labels, or Other Controls on Caffeine Use The risks of caffeine intoxication are underrated, and only a few products include warnings, which increases the probability of exposing the consumer to unknown effects of the commodity.
• Aspirin, Acetaminophen, Ibuprofen, Naproxen, Caffeine: Analgesics Analysis The reduced synthesis of prostaglandins prevents the brain from receiving information of pain and inflammation while the reduced synthesis of thromboxanes hinders the formation of blood clots.
• The Effect of Caffeine on Pulse and Respiration Rates The bodily effect of caffeine, known by its chemical name of 1,3,7-trimethylxanthine, is thought to be related to the production of energy in the form of adenosine triphosphate. The aim of this experiment is to […]
• Decaffeinated Coffee Is Not Caffeine-Free This is what triggered the research fronted by the Professor to determine the degree of caffeine in decaffeinated coffee brands, in the market.
• The Effect of Caffeine on the Blood Glucose Level The goal of the investigation was to explore the effect of caffeine on the blood glucose level. The only difference between the two groups was the administration of plain water to one group and the […]
• Consumption of Caffeine Is Associated With Reduced Risk of Parkinson’s Disease The risk of the disease was found to reduce more progressively with the increase in the level of coffee consumption. Some observers argue that the level of reduction in cases of PD amongst coffee drinkers […]
• Cardiovascular Disease and Caffeine Effects There have been conflicting ideas about the effects of caffeine on the body especially in relation to the development of cardiovascular diseases. The increased prevalence of cardiovascular diseases is mainly due to the changes in […]
• Caffeine Addiction and Negative Effects The thesis of this paper is that scientists need to reclassify caffeine as a potentially addictive stimulant drug. In addition to the potential to cause addictive behavior, caffeine can have an adverse effect on the […]
• Physical Performance Among Athletes: The Impact of Caffeine Consequently, the proposed research topic is the investigation of caffeine’s effect on physical and cognitive performance among athletes who are not used to the continuous intake of this element.
• Caffeine: Absorption, Distribution, Metabolism Immediately after the consumption of caffeine, the paraxanthine and caffeine concentration increases in the body within 8 to 9 hours and it leaves minute traces of toxicology into the blood. The sudden cessation in the […]
• Effects of Caffeine on Open Field Behavior of the Rat It was studies the psychological function of behavior of rats and the influence of caffeine on it through 8-9 weeks from the beginning of application of caffeine.
• Caffeine Consumption in Personal Experience It is possible to note that, in the case of tolerance, the situation is somewhat similar to the consumption in general.
• Caffeine: Does Acute Consumption Affect Aerobic Performance? The research regarding the connection between caffeine consumption and one’s response to exercising is replete with studies failing to find any significant effects of the stimulant on people’s vitals.
• Caffeine and Its Positive Impacts on Mental Activity The increased level of these neurotransmitters results in increased neuron activity in the body. That being the case, the affected individuals will be forced to consume high doses of coffee in order to increase the […]
• Prenatal Caffeine Exposure’ Effects To prove the hypothesis, the authors conduct the experimental study that delves into the investigation of the major concerns of the issue.
• Caffeine: Carriers, Addiction and Diseases When caffeine is taken in, the body absorbs and then gets rid of it fast. But, generally, it creates no threat to the physical and social aspects of health, like the addictive drugs do, though […]
• Why College Students Should Not Turn to Caffeine The paper will look at some of the trend of involvement of college students into caffeine consumption and the risks that surround consumption of caffeine by college students.
• Caffeine and Its Effects on Brain: Long-Term Physiological Changes
• The Confusion and Inconsistencies About the Effects of Caffeine
• Caffeine and Bicarbonate for Speed: A Meta-Analysis of Supplements Potential for Improving Intense Endurance Exercise Performance
• Insomnia: Sleep and Caffeine Related Components
• Caffeine and Global Spatial Processing in Habitual and Non-habitual Caffeine Consumers
• Cognition and Brain Activation in Response to Various Doses of Caffeine: A Near-Infrared Spectroscopy Study
• Caffeine, Stress, and Proneness to Psychosis-Like Experiences
• The Alarming Aspects and Effects of Caffeine
• Caffeine and Energy Drinks: High Levels of Stress
• Alcohol, Caffeine, and Nicotine: The Most Widely Consumed Psychotropic Drugs Worldwide
• Caffeine Enhances Memory Performance in Young Adults During Their Non-optimal Time of Day
• Combination Ergotamine and Caffeine Improve Seated Blood Pressure and Presyncope Symptoms in Autonomic Failure
• Caffeine and Its Effects on the Human Body and Society
• Prenatal Nutrition: The Effects of Caffeine and Green Tea
• Caffeine Consumption and the Number of Sleep Needed
• Natural Product Extraction: Isolation of Caffeine From Tea, Thin Layer Chromatography
• Caffeine: The Health Benefits of Drinking Coffee, or Anything With Caffeine in It
• Caffeine Controls Glutamatergic Synaptic Transmission and Pyramidal Neuron Excitability in Human Neocortex
• Blood and Caffeine: Behavioral and Side Effects of Caffeine
• Caffeine Citrate for Apnea of Prematurity: A Prospective, Open-Label, Single-Arm Study Neonates
• Caffeine Consumption During Pregnancy Accelerates the Development of Cognitive Deficits in Offspring
• Association Between Plasma Caffeine and Other Methylxanthines and Metabolic Parameters in a Psychiatric Population Treated With Psychotropic Drugs Inducing Metabolic Disturbances
• Caffeine and Modulate of Food Intake Depending on the Context That Gives Access to Food: Comparison With Dopamine Depletion
• Improved Exercise Tolerance With Caffeine and Modulation of Both Peripheral and Central Neural Processes in Human
• Chlorpheniramine and the Analgesic Effect in Migraine of Usual Caffeine, Acetaminophen, and Acetylsalicylic Acid Combination
• Caffeine and Responsiveness With Different Individuals
• Energy Drinks and the Neurophysiological Impact of Caffeine
• Coffee With High Caffeine Content Augments Fluid and Electrolyte Excretion at Rest
• Caffeine and Parkinson’s Disease: Multiple Benefits and Emerging Mechanisms
• Individual Differences Affecting Caffeine Intake
• Caffeine Addiction and Chronic Fatigue Recovery
• Caffeine and Selective Adenosine Receptor Antagonists as New Therapeutic Tools for the Motivational Symptoms of Depression
• Legal Drugs: Caffeine’s Effects
• Caffeine Consumption and General Health in Secondary School Children: A Cross-Sectional and Longitudinal Analysis
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How much caffeine is OK, according to a caffeine expert

A caffeine researcher explains how much coffee and soda is too much.

I started drinking coffee when I was in middle school. Since then, I’ve grown into what I think of as an “avidly caffeinated person.” My morning cup of coffee prevents a headache, cups two and three get me through my morning writing, and cup four is a nice little cap to my afternoon. Coffee is a big part of my day, and I love it. But lately, I’ve been wondering how much daily caffeine is the “right” amount.

As you’ve likely heard by now, Panera has faced several lawsuits in recent months, with its “ Charged Lemonade ” at the center of each. This lemonade contains almost as much caffeine per serving as is recommended in an entire day, and the lawsuits allege that multiple people have died as a result of consuming it. In turn, Panera has changed its approach to the lemonade, changing its labels and keeping it behind the counter, away from its self-serve drinks. ( As of now , however, the restaurant is still selling it .)

Since the emergence of the Panera lawsuits, I’ve found myself wondering about my own caffeine consumption. Is my normal routine too much? If I have a work deadline to meet, would it be dangerous to add one more cup in the afternoon?

Your caffeine consumption is probably fine

To get the answers to these questions, I connected with Jennifer Temple , Director of the Nutrition and Health Research Laboratory at University at Buffalo. Temple’s research includes, among other things, the effect of caffeine on the body.

“Whatever you’re doing is probably fine,” said Temple after I had explained my conundrum. She went on to explain that under normal circumstances, which for most people means slow consumption of about 100 mg of caffeine per serving, our bodies have a pretty solid ability to cut us off when we’re consuming caffeine. The stimulant is metabolized in about 10 minutes, and when we’ve had too much, our bodies have numerous ways of letting us know.

“It varies from individual to individual and can be hard for people to put into words,” said Temple. “It’s a combination of jittery and nauseous. You start to feel shaky, your stomach doesn’t feel quite right. Some people report that their heart starts racing, or they might feel dizzy, have an urgency to urinate, they might report feeling kind of anxious. It’s a combination of cardiovascular symptoms that are tied to more emotional response.”

Just about everything Temple said resonated with me. I know very well the feeling of making that extra cup of coffee and then, a few sips in, as it starts to metabolize, realizing that it’s not making me feel great. At that point I usually just stop drinking it, which is apparently true for most people.

“Surveys suggest that regular caffeine consumers basically titrate the amount they drink based on how it makes them feel,” said Temple. “You know when you’ve had too much, and you stop drinking.”

Some people tolerate caffeine better than others

Temple said that studies on the upper limits of caffeine tolerance are limited, because it wouldn’t be ethical to toy with giving people too much caffeine, as caffeine overdose can cause cardiac arrest and death.

For the most part, though, healthy adults are able to consume around 400 mg of caffeine daily , roughly the equivalent of four mugs of home-brewed coffee. Still, Temple said, there are some people who drink more than on a daily basis and have no ill effects.

Why drinks like Panera’s Charged Lemonade can be dangerous

In the case of a highly caffeinated lemonade, like the one involved in the Panera lawsuits, there are a few things that could contribute to trouble.

The first is that Panera’s Charged Lemonade contains more caffeine than even some energy drinks do. Moreover, lemonade is a drink that practically no one associates with caffeine. Lemonade is so dissociated from caffeine, in fact, that Temple has used it in studies where she needs a placebo to a caffeine drinker and needs the person drinking it to absolutely believe they are not drinking caffeine.

“We use lemonade when we’re trying to remove expectancy,” she said. “We use it as a neutral beverage [in which] no one would ever expect caffeine.”

That means that without proper labeling and warnings, it’s plausible that customers could consume caffeinated lemonade without realizing it’s caffeinated, or could give it to their child without realizing it has caffeine.

Also, for the most part, people sip coffee slowly, in part because we know that if we down too much caffeine all at once, we might feel sick. Coffee is a delight, but it isn’t necessarily thirst-quenching. Lemonade, on the other hand, is famously refreshing , and I definitely drink lemonade in a different manner than I do coffee—often, I gulp it down. If I were to unwittingly drink a bunch of caffeinated lemonade, I might already have consumed too much by the time I figured it out.

“One of the dangers is that because lemonade can be so quickly consumed, you might feel those signals that are telling you to stop drinking caffeine, but you’ve already had too much,” said Temple.

Caffeine overdose is very dangerous, but also very rare

Temple said that caffeine overdose is exceedingly rare, largely because of the warnings our bodies give us when we’re consuming caffeine under normal conditions (relatively slowly and in normal amounts). But when it does happen, it affects the heart and can lead to cardiac arrest and death. Which is why it’s especially important that when products do contain caffeine, particularly in high doses, it’s made very, very clear to consumers via labeling.

Unfortunately, Temple says there’s not a drug to reverse the effects of too much caffeine, the way Naloxone can reverse the effects of an opioid overdose. As a result, the best tool we have in our toolbox is to be mindful consumers. This means drinking caffeine in doses we know we’re generally able to handle, listening to our body when it tells us we’ve had enough, and being aware and careful when we’re consuming things we don’t typically associate with caffeine, like lemonade and noodles .

A version of this article originally appeared on The Takeout .

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7 Hidden Sources Of Caffeine

You might count on the caffeine in your morning cup of coffee or tea to boost your mood, energy and focus. But you may also get additional caffeine from other foods and drinks without realizing it. Too much caffeine can cause undesirable side effects ranging from anxiety to digestive problems. 

“Tracking how much caffeine you have each day is important. Many people are unaware that caffeine is in many foods and drinks, including decaf coffee and tea, non-cola sodas and snack bars,” says Sarah Hutchinson, RDN , a registered dietitian at Henry Ford Health. “Monitoring caffeine is important if you’re sensitive to it, trying to avoid it or want to reduce its side effects.”

What Is Caffeine?

Caffeine is a stimulant that acts on the central nervous system. It naturally occurs in many plants, leaves and seeds. You may be familiar with some of its sources, including coffee and cocoa beans and tea leaves. It’s also in guarana, a Brazilian plant found in the Amazon, and kola nuts, native to West Africa.

Caffeine can offer health benefits, such as improved mood, focus, memory and concentration. Certain beverages that contain caffeine, such as coffee, have been shown to improve liver health . But too much caffeine can cause side effects , including:

• Dehydration
• Digestive problems
• Increased heart rate and blood pressure
• Sleep disturbances  

Everyone reacts to caffeine differently. Hutchinson recommends limiting caffeine to 300 to 400 milligrams per day. That equals about two to three eight-ounce cups of coffee (100 to 150 milligrams of caffeine). Most teas have less caffeine. Black tea contains 50 to 80 milligrams per cup, while green tea has 20 to 30 milligrams.

Some people, including children and teens, are more sensitive to caffeine and need to limit it. People who may want to avoid caffeine include those with:

Meet With A Dietitian

• Anxiety disorders
• Heart rhythm problems (arrhythmia)
• High blood pressure (hypertension)
• Sleep disorders
• Ulcers or gastroesophageal reflux disease (GERD)

Surprising Foods And Drinks That Contain Caffeine

Even if you can tolerate more caffeine than you bargain for, you may be unaware of all the foods and drinks that contain it. Here, Hutchinson highlights foods and beverages to keep in mind as you make your caffeine budget:

1. Chocolate

 Any food flavored with cocoa contains caffeine, including baked goods, beverages and ice cream. The amount of caffeine varies depending on the item.

2. Decaffeinated coffee and tea

The Food and Drug Administration (FDA) only requires manufacturers to remove 97% of caffeine from “decaffeinated” products. A cup of decaffeinated coffee may still contain 2 to 15 milligrams of caffeine. 

3. Kombucha

This fermented tea is a popular beverage for gut health. Like yogurt and kimchi, kombucha contains probiotics. But it also contains caffeine, which could lead to distress for some people with gastrointestinal conditions.

4. Matcha and yerba mate

These herbal teas have significant caffeine. A cup of matcha tea has about 49 milligrams and a teaspoon of matcha powder has 88 milligrams. A cup of yerba mate tea can have up to 80 milligrams. Both types of tea can also be found in processed foods like ice cream and baked goods.

5. Snack bars

Brands marketed as sources of nutrition and energy may contain caffeine from chocolate, coffee beans or extracts, guarana, matcha or yerba mate tea.

6. Non-cola sodas and bottled water

Kola nuts used to flavor cola-flavored sodas may also be used in orange- or lemon-lime-flavored sodas. While a cola contains about 47 milligrams of caffeine per 16-ounce bottle, a non-cola soda can have about 78 milligrams. Bottled waters marketed as energy drinks often contain caffeine. 

7. Supplements

Over-the-counter pre-workout, weight-loss and energy supplements can contain caffeine. The FDA does not regulate supplements, and the amount of caffeine may vary by product. Hutchinson recommends talking with your doctor before taking supplements to ensure they are right for you.

How To Spot Caffeine In Food And Beverage Labels

The FDA doesn’t require manufacturers to list caffeine on food and beverage labels, so tracking how much is in specific foods and beverages can be challenging.

Hutchinson says you can still spot caffeine in many products. “Look for ingredients like cocoa, coffee or mocha flavoring. Matcha, yerba mate, guarana and kola nuts also signal the presence of caffeine,” she says. 

You can also check online menus if you’re planning to go out to eat. Some restaurants list menu item ingredients on their websites. 

When it comes to monitoring caffeine intake, Hutchinson recommends listening to your body. “Cut back on caffeine and find substitutes if you’re anxious or have other side effects. If you can’t function without caffeine, you may have a sleep disorder or other underlying health condition. Talk with your doctor about your caffeine intake to determine what amount is safe for you,” she says.

  Reviewed by Sarah Hutchinson, RDN , a registered dietitian for the Center for Health Promotion and Disease Prevention.

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Here's exactly when to stop drinking caffeine for the best chance of a great night's sleep

Discover a good caffeine cutoff time, plus when and why it’ll vary

Can’t start your day without a hearty dose of coffee? Regularly brew a cup of green tea after lunch? While these caffeinated drinks offer health benefits that go beyond helping you perk up and stay focused, relying on them in high quantities and/or drinking up too late in the day could mean bad news for your shuteye come nightfall, and having even the very best mattress may not be enough to lull you off to sleep.

If you can’t bear to part ways with your go-to sources of caffeine, it’ll be in your best interest to at least cap off intake at a certain point in the day; it's also useful to know that the best time in the morning to drink coffee is 10am, not first thing.

We spoke to a dietician to discover if there’s an ideal time to stop caffeinating for the sake of better sleep, and also learned why caffeine and sleep are at odds with each other, as well as finding out about some surprising sources of the stimulant you may also want to steer clear of.

When should I stop drinking caffeine before bed?

“It is suggested that most people should stop consuming caffeine at least six hours before bedtime [to avoid] disruptive effects on sleep,” says Amy Shapiro, MS, RD, CDN, founder and director of Real Nutrition in New York City.

According to a 2013 study published in the Journal of Clinical Sleep Medicine , participants who consumed 400 milligrams of caffeine 0, 3, or 6 hours before their regular bedtime led to significantly disturbed sleep compared to placebo groups.

People who are sensitive to caffeine and/or have ongoing sleep issues may want to cease caffeinating even earlier than the six-hour mark. On the other hand, some may take to a post-dinner shot of espresso just fine and have no difficulty catching their ZZZs within a few hours’ time.

In short, the ideal caffeine cutoff time will be based on the individual, so the six-hour mark is a decent general guideline. “The timing may vary due to the high variability of individual responses to caffeine consumption based on sex, age, diet, health, metabolism etc.,” Shapiro explains. “Depending on the individual, the effects of caffeine consumption can last up to 12 hours.”

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The amount of caffeine present in the beverage will also play a role, she adds. For example, a large cup of coffee can pack over 400 milligrams of caffeine, while a bottle of iced tea can offer 20 to 50 milligrams per serving. Caffeine content will vary based on factors such as the size of the drink, brands, and brewing times.

What caffeine does to your body

“Caffeine is a stimulant that increases activity in your brain and nervous system, and increases circulation of neurotransmitters including cortisol and adrenaline,” Shapiro explains. (Cortisol is known as the stress hormone yet it also helps us stay alert. Similarly, adrenaline helps prepare us for fight-or-flight mode and allows us to react quickly.)

Short-term effects of caffeine, she continues, typically include:

• Mental alertness
• Physical energy
• Increased breathing
• Faster heart rate

Caffeine isn’t without its risks. Shapiro warns that high doses, frequent use, or potential adverse effects may include:

• Restlessness
• Physical and/or psychological dependence

Why caffeine disrupts sleep

Most people reach for caffeine since it helps them stay awake, so it makes sense that it’d be at odds with falling asleep.

“Caffeine acts primarily on receptors in the body that are related to functions of the brain associated with sleep, arousal, and cognition,” Shapiro explains. “Adenosine receptor agonists in the brain generally promote sleep, and caffeine promotes wakefulness by antagonizing [i.e., inhibiting or counteracting] those receptors.”

In other words, caffeine disallows certain sleepiness cues to kick in when they should—which is how coffee, caffeinated tea and the like can prevent a good night’s rest.

In addition to affecting sleep latency (i.e., the time it takes to fall asleep), caffeine may also worsen sleep quality. In a 2021 randomized controlled trial in healthy men, published in the Journal of Biological Rhythms, those who had 150 milligrams of caffeine three times in the daytime over 10 days experienced the following sleep issues compared to a placebo group:

• Delays in REM sleep (a sleep stage that heavily influences subjective sleep quality)
• Greater difficulty waking up
• Feeling more tired upon arising

What foods and drinks contain caffeine?

You likely already know that coffee, some teas (namely black and green tea), and energy drinks contain caffeine. However, they’re not the only dietary items that pack the stimulant.

According to Shapiro, additional sources of caffeine you may want to cut off by the afternoon include:

• Soft drinks, such as soda
• Some protein bars
• Chocolate/cacao
• Some medications

Moreover, it’s worth remembering that the terms ‘decaf’ and ‘caffeine-free’ aren’t interchangeable. The former indicates that caffeine was removed from a given product and trace amounts will likely remain present. Meanwhile, the latter indicates that caffeine wasn’t in a given product (such as the majority of herbal teas ) to begin with.

The takeaway

If you struggle to fall asleep at night, you may find relief by ceasing caffeine intake 6 hours before bedtime. However, since caffeine tolerance varies by the individual, you might need to extend this timeline, sometimes to as long as 12 hours.

It could also benefit your ZZZs to reduce the amount of caffeine you consume (i.e., going from two cups to one cup daily) or perhaps even slowly taper off caffeine entirely.

Last but not least, you can always add items that promote better rest—such as chamomile tea and tart cherry juice—into your nightly regimen.

Amy Shapiro MS, RD, CDN, has been the founder and director of Real Nutrition, an NYC-based private practice, for over 15 years. She is dedicated to healthfully and successfully guiding clients to their optimal nutrition, weight, and overall wellness. Recognized for her individualized, lifestyle-focused approach, which integrates realistic food plans, smart eating habits, and active living. 

Michele Ross is a freelance wellness, beauty, and lifestyle writer based in Los Angeles. She contributes to publications including Well+Good, Editorialist, and RealSelf; has worked with brands including HUM Nutrition, Goldfaden MD, and Beast Health; and has served as a content strategist and ghostwriter for doctors and dietitians. Her goal is to empower readers to make informed decisions about their routines that work for their specific needs and concerns.

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I followed Apple CEO Tim Cook's morning routine for a week. It left me exhausted and with a budding caffeine addiction.

• I've been trying to implement a productive morning since moving for work in January.
• I decided to challenge myself and copy the morning routine of Apple CEO Tim Cook .
• There's no way I'll ever wake up as early as him, but I did start to enjoy a morning coffee.

Since moving to the New York metropolitan area in January, I've been working on establishing a productive morning routine to help me succeed in my transition to adulthood.

You know, that scary thing everyone warns you about when you graduate from college.

So far, adjusting to the 9-5 life has been exactly that: an adjustment. And while I haven't quite reached the same levels of existentialism as some of my fellow Gen Zers (give me time), I've definitely felt that I'll never finish my never-ending to-do list.

During my first week of work, I was ready to sleep by 8 p.m. and truly couldn't fathom how anyone had the motivation or energy to work out, let alone raise a family or be social, which prompted a very empathetic phone call to my parents.

I've found a much better rhythm since then, but the experience got me thinking: What kind of productive person could I emulate to achieve my goals better?

CEOs are famously at the top of their games — known for their extensive industry knowledge, packed Google calendars, and ability to lead others. As someone just beginning my career, I couldn't think of a better position to aspire to.

The next question was: Which CEO? Mark Zuckerberg's daily routine starts with running and MMA training, so that was an immediate no from me. But Apple CEO Tim Cook wakes early — 4 to 5 a.m. early — responds to emails, does strength training several times a week, then showers, gets ready, and has some coffee and maybe a light breakfast. Minus the early wake-up time, his routine seemed very approachable, with realistic opportunities to integrate healthier habits into my own life.

With my decision made, I was excited to begin a weeklong challenge to see if copying Cook's routine would help kick-start my own productivity.

Here's how it went.

I used Monday night to prepare for Tuesday's early wake-up time, finishing chores, and going to bed early to ease the transition.

I know challenges like this would normally start on Monday morning, but during the week I chose to complete it, the combination of daylight-saving time and a late night watching the Oscars left me needing a bit more time to prepare for this massive change in routine.

In a 2023 episode of " Dua Lipa: At Your Service ," Cook said he's "an early bird" who usually wakes up between 4 and 5 a.m.

The benefits of waking up early can include putting you in a better position to succeed, Business Insider previously reported.

"Morning people also anticipate problems and try to minimize them, my survey showed," Christoph Randler, a biologist, told the Harvard Business Review in 2010, referring to his study of college students. "They're proactive. A number of studies have linked this trait, productivity, with better job performance, greater career success, and higher wages."

I normally go to sleep between 11 p.m. and midnight and wake up around 7:30 a.m., so I decided to take a pretty liberal approach to Cook's routine and set my alarm for 4:45 a.m., planning to go to sleep by 10:30 p.m.

I work from home on Mondays, so I could immediately transition into completing the household chores and minor tasks I'd put off during the weekend.

By 10 p.m., my kitchen was clean, laundry was folded, outfits for the gym and work were picked, and my night routine was complete — which never happens. I allowed myself 30 minutes of TikTok time because I still can't seem to stop making the mistake of watching screens before bed , then I shut off my phone and did my best to fall asleep.

Day one started productively with an at-home Pilates workout.

I don't think anything can truly incentivize you to wake up at 4:45 a.m. except maybe a flight to a tropical vacation, and since this wasn't a vacation, I was very disappointed to be up so early.

But apparently, that's not how Cook feels. On "Dua Lipa: At Your Service," he said he spends his first hour on email.

"I'm pretty religious about doing this," he said. "I read emails from a lot of customers and employees, and the customers are telling me things that they love about us or things that they want changed about us. Employees are giving me ideas. But it's a way to stay grounded in terms of what the community is feeling, and I love it."

There's no way my inbox is anywhere near as full as his, so I checked my ad-filled email and read a few Slack messages before drifting back to sleep.

I awoke again at 6:20 a.m. and promptly put on my gym clothes and contacts, then headed to my living room for a workout.

Cook, who's 63, told Lipa, "I spend an hour in the gym, usually doing strength training, and I've got somebody to really push me to do things I don't want to do, and I do no work during that period of time at all. I never check my phone."

Cook might have a trainer, but I have "Pilates Body by Raven" YouTube videos. Although I only worked out for about 30 minutes, the activity helped me wake up, and it felt good to push myself by trying something new.

Since I quit playing soccer after high school, I've struggled to maintain a consistent workout routine. Typically, I work out for a couple of days or weeks, then do nothing again for months at a time, so it was exciting to find a new activity I enjoyed. It motivated me to believe this could be part of my normal routine.

Watching the sun rise over New York City was a special moment that made me feel accomplished.

After my workout, I stopped to look at the sunrise, something I'm never awake to appreciate, and then it was time to get ready for work.

I showered and dressed, but waking up so early gave me a false sense of time security, so I actually ended up running late and skipping breakfast to make it to the office on time.

Overall, my first impressions of this new routine were positive.

Although I felt a bit tired by midafternoon, day one felt like a success, and I was happy to have had a productive start to my day with a workout already completed so I could relax when I got home.

On Wednesday, I struggled to wake up early but enjoyed taking the time to make breakfast and coffee.

I went to bed on Tuesday between 10:30 and 11 p.m. and felt like I'd barely slept when I tried to wake up at 5 a.m. I'm sure the Pilates had something to do with that.

Through half-opened eyes, I quickly scanned my email and Slack notifications before letting myself go back to sleep. When I woke up again, I used TikTok to put off working out before finally forcing myself to at least do something.

I settled on a quick 20-minute strength workout consisting of crunches, leg lifts, push-ups, and some "weight lifting," aka me lifting my cute, light-green, 6-pound weights from Target.

Since I was working from home, I had time to make breakfast after showering and getting dressed.

During a 2017 interview with Andrew Ross Sorkin, a columnist at The New York Times, Cook "dug into scrambled egg whites, sugar-free cereal, unsweetened almond milk, and bacon." He also usually gets coffee.

I don't like bacon and didn't have any sugar-free cereal, so I made scrambled egg whites and a cup of coffee with sugar and unsweetened vanilla almond milk.

Even though I don't normally drink coffee (I didn't even like how mine tasted), I continued to sip from my mug long after its contents turned cold, so I guess that means it worked — or that I needed it.

Throughout the day, I felt energized and was proud of myself for pushing to get in a small workout, even though I didn't succeed in every aspect of the routine.

I was beginning to see some practical room for improvement in my life outside the challenge.

Thursday was the best day of the week by far. I felt energized, strong, and ready for the busy day ahead.

I felt more awake on Thursday than I had the past two days, despite falling asleep around midnight on Wednesday.

Did that mean I jumped out of bed to start my workout? No, but it did give me extra time to charge my phone since I had forgotten to do so the night before. Then I got out of bed at my "new normal" of 6 a.m. and did another "Pilates Body by Raven" video, this time focusing on strengthening my core.

I may not be a fan of Cook's wake-up time, but I do need to thank him for not being a cardio person. I finished my workout in 30 minutes, showered, and got dressed, but I didn't have enough time to cook egg whites. So I decided to pick up breakfast at the Dunkin' near my office.

My iced vanilla latte was the perfect treat and motivation for a busy day at the office.

I picked up an iced vanilla latte and treated myself to a glazed doughnut.

Despite failing to cook eggs at home and falling short of completing Cook's entire morning routine , Thursday was the first day I felt things were starting to change.

I tend to be a bit delusional and think I can see results a few days into trying something new. Still, I felt stronger during my workout and more awake throughout the day, and I don't think it was just a coincidence.

Regular exercise helps boost energy, as well as improve focus and mood. Knowing that I was beginning to experience some of these benefits made me want to keep waking up early to exercise once the challenge was over.

I met up with a friend from college and some coworkers after work for happy hour, so I got home later than usual but fully satisfied with the energy I had to get everything done.

Friday morning, however, was a rude awakening. I woke up beyond exhausted and ditched the routine entirely.

Just when I felt like I had everything figured out, it fell apart.

I wish I had a photo to document the chaos that was me on Friday, but instead, all I can offer is a photo of how organized I was on Wednesday so you can imagine the opposite.

My whole body was sore from the workouts, and I was just so tired. It was disappointing to feel such a complete shift from Thursday to Friday; it felt like all the adrenaline and internal motivation that had been pushing me forward throughout the week crashed.

My only goal for the day was to get through it, but I think that was an important lesson in this experiment, too.

At 22, I have no desire to become a CEO anytime soon, but the experience helped me gain a new perspective on productivity.

Trying a challenge like this one was really helpful in shaping my overall perspective on productivity, but I wouldn't recommend expecting to make big changes like this overnight. Changing what time I go to sleep, figuring out what days I like to work out, and understanding when my body needs rest will take time, and rushing results only contributed to my Friday morning crash … and subsequent weekend slump.

At 22, I have no plans to become the CEO of a multibillion-dollar company anytime soon — Cook was 50 when he took the reins at Apple , after all — so comparing myself to someone with significantly more life experience and resources would be a waste.

Instead, this challenge has helped me recognize that my life as a reporter doesn't need to start at 5 a.m. to be "productive," but I can understand how good it feels to work out in the morning and, of course, enjoy an iced vanilla latte now and then.

• Main content

The Nespresso Coffee Pod That Has The Most Caffeine

N espresso pods are great for making coffee at home, especially since they're compatible with some of the best coffee pod machines available, but sometimes, you prefer a pure caffeine kick over a smooth taste. While Nespresso pods' levels of intensity are reflected on the brand's website, the precise caffeine content is not, begging the question, which pod provides the biggest caffeine boost?

This appears to be a fairly common question, appearing as a top-five FAQ on Nespresso's website . The FAQ explains that, while most coffee pods have a similar caffeine level, those meant for higher volume beverages consequently have a higher level of caffeine. The FAQ specifically mentions the Carafe Pour-Over Style pod, which contains "over 200mg of caffeine per complete capsule serving." A double shot of espresso will usually have between 58 and 185 milligrams of caffeine, so caffeine content exceeding 200 milligrams is pretty impressive.

Of course, this is based on a slight technicality. Because the pour-over pods are intended to be served in an 18-ounce carafe or 12-ounce cup, a significantly larger measurement than the 1.35-ounce cup recommended for an espresso pod, the caffeine is distributed throughout a much larger volume of liquid. The FAQ states that an espresso pod normally contains between 50 and 100 milligrams of caffeine, so if served correctly, the pour-over pod won't feel quite like the adrenaline shot you'd expect.

Read more: How To Get More Flavor From Your Coffee Pods & Other Keurig Hacks

Which Single-Serving Nespresso Pods Have The Most Caffeine?

While there's no reason you can't use the pour-over pod in a single serving, it won't do your taste buds or your wallet any favors. Espresso pods cost between 85 and 90 cents per capsule, whereas pour-over pods come in at $1.65, almost double the price. The pour-over pods are optimized for higher volumes of liquid, so the taste may seem overly strong and bitter if used for a short drink. In theory, you could reuse the pod , but the quality of the drink takes something of a nosedive.

Luckily, there are some single-serving exceptions to the 50 to 100-milligram rule (although they don't surpass 200 milligrams like pour-over capsules). According to Nespresso's FAQ, Vertuo coffees contain a caffeine content ranging between 170 and 200 milligrams. They're best served as 2.7-ounce double shots, but if you use Nespresso pods for the energy boost rather than to sample the best flavors , you're likely well acquainted with double shots already. These pods are naturally more expensive than single-shot capsules and will set you back between $1.15 and $1.25, depending on which pod you choose.

Read the original article on Mashed .

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Caffeine Intake among Undergraduate Students: Sex Differences, Sources, Motivations, and Associations with Smoking Status and Self-Reported Sleep Quality

Aina riera-sampol.

1 Research Group on Evidence, Lifestyles and Health, Department of Nursing and Physiotherapy, Research Institute of Health Sciences (IUNICS), University of the Balearic Islands, 07122 Palma, Spain; [email protected]

2 Health Research Institute of the Balearic Islands (IdISBa), 07120 Palma, Spain

Lluis Rodas

3 Research Group on Evidence, Lifestyles and Health, Department of Fundamental Biology and Health Sciences, Research Institute of Health Sciences (IUNICS), University of the Balearic Islands, 07122 Palma, Spain; moc.liamtoh@sadorsiull

Sonia Martínez

Hannah j. moir.

4 School of Life Sciences, Pharmacy and Chemistry, Faculty of Science Engineering and Computing, Kingston University London, Penryhn Road, Kingston upon Thames KT1 2EE, UK; [email protected]

Pedro Tauler

Associated data.

The data presented in this study are available on request from the corresponding author.

Due to its stimulatory effects, caffeine is one of the most frequently consumed mood and behavior altering drugs. University students report using caffeine-containing products to enhance mood and performance or for a desire of alertness. The current study investigated caffeine consumption in university undergraduate students, and associations with smoking status, alcohol and cannabis consumption, fruit and vegetable consumption, and sleep quality. Motivations for caffeine intake were also ascertained. A total of 886 undergraduates aged 18–25 years from the University of the Balearic Islands participated in a cross-sectional survey. Caffeine was consumed by 91.1% of participants. Caffeine consumers were more likely to be female, smokers, and alcohol and cannabis consumers. Coffee was found to be the main source of caffeine intake in both men and women (48.9% of total caffeine intake). Higher percentages of women consumed coffee (56.4 vs. 42.1%, p = 0.01) and tea (40.3 vs. 19.8%, p < 0.001), whereas a higher percentage of men consumed energy drinks (18.0 vs. 7.4%, p < 0.001). Main motivations for caffeine intake were those related to cognitive enhancement. Caffeine intake was associated with poorer subjective sleep quality ( p < 0.001). In conclusion, undergraduate students that were female and smokers reported higher caffeine intakes. Coffee was found as the main caffeine contributor, with higher contributions of tea in women and energy drinks in men. Universities should consider the implementation of health campaigns and educational programs to educate students of the risks of high caffeine consumption together with associated behaviors such as smoking, alcohol consumption and poor sleep quality to physical health and academic performance.

1. Introduction

Caffeine is one of the most frequently consumed mood and behavior altering drugs [ 1 ]. The stimulatory effects of caffeine together with its widespread presence in foods such as coffee, tea, and chocolate are important reasons to explain the high prevalence (around 80%) of caffeine consumption around the world [ 1 ]. Regarding caffeine sources, in most European countries, except for the United Kingdom and Ireland, coffee has been commonly found to be the major source for adults [ 2 ].

Data from the 2007–2012 National Health and Nutrition Examination Survey (NHANES), reported that consumption of caffeine in U.S. adults was on average, 169 mg/day [ 3 ]. In Western Europe, including Spain, the average daily intake of caffeine is as similar to the U.S. [ 2 ]. In addition, similar or slightly lower figures for caffeine intake have been found in university [ 4 , 5 ] and in college students [ 6 ], or in participants of a similar age [ 2 ], with coffee as the main caffeine source. However, to our knowledge, no study has reported caffeine intake in university students from a South European and Mediterranean country such as Spain. Such countries have different coffee preparations (“cortado” or “café con leche”), and significant different dietary characteristics including the schedule and the energy distribution of the meals, and different working and teaching schedules.

Demographic factors such as sex, together with habits such as alcohol consumption and tobacco use have been associated with caffeine intake [ 3 ]. Regarding sex, studies performed in university students, or in participants of a similar age, have reported higher prevalence of caffeine consumption in women than in men [ 6 ], or a higher daily caffeine intake, but only when expressed as per kg body weight [ 4 ], because when expressed as the absolute value, no differences have been observed [ 4 , 6 ]. Therefore, it would be of interest to determine whether differences are related to sex differences in weight or for other reasons.

Previous studies have reported higher caffeine intake in smokers than in non-smokers in general population [ 7 , 8 ] and in college students from the USA [ 6 ]. Furthermore, a higher probability for smokers to exceed the recommended caffeine intake was also found in university students from New Zealand [ 4 ]. Notably, smokers may consume more caffeine because smoking upregulates the main metabolic pathway of caffeine [ 9 , 10 ], which could indicate that smokers may need to drink more caffeine to experience similar effects as non-smokers. However, characteristics of the diet, such as fruit and vegetable consumption, or the use of substances such as cannabis have not been commonly considered in relation to caffeine intake.

The main reasons reported for use of caffeine-containing products are usually related to the stimulant effects of caffeine, including to reduce fatigue, increase alertness or to enhance physical performance [ 2 ]. Adolescents state they use caffeine to provide more energy, for the taste of the product, and for image enhancement [ 11 ]. University students reported using caffeine-containing products to enhance mood and performance [ 6 ], or for a desire of alertness [ 12 ]. Furthermore, in a supplementation study, university students perceived that they were significantly more alert, awake, clear-minded, and able to concentrate after ingesting low doses of caffeine, with such effects being desirable for academic work [ 13 ].

Higher caffeine intake has been commonly associated with poorer subjective sleep quality in adults [ 14 ]. Furthermore, a higher prevalence of poor sleep quality has been found among consumers of energy and stimulant drinks [ 15 ]. However, most of the studies examined the association of subjective sleep quality with prevalence of caffeine sources’ consumption rather than with the overall daily caffeine consumption as a continuous variable. In addition, the influence of sex should be considered when determinants of subjective sleep quality are analyzed because a poorer subjective sleep quality in women than in men has been commonly found, at least among university students [ 16 , 17 ].

The aim of the study was to determine caffeine and caffeine sources’ consumption among undergraduate students from the University of the Balearic Islands. The motivations students reported for caffeine consumption were also ascertained. The association between caffeine intake and demographic variables such as sex and age, smoking status, and fruit and vegetable consumption were analyzed. Furthermore, the association of caffeine intake with subjective sleep quality was also analyzed. The main hypothesis of the study was that caffeine intake could be associated with smoking and with a poorer sleep quality.

2. Materials and Methods

2.1. study design and participants.

A descriptive cross-sectional study was performed in a convenience sample of university undergraduate students in March 2021. Participants could be included in the study if they were currently engaged in any undergraduate course in the University of the Balearic Islands and aged 18–26 years old. Participants completed, online and in a voluntary and completely anonymous fashion, a survey designed using the Google Forms web tool. The survey was distributed among university undergraduate students through announcements on the virtual learning environment, ‘Moodle’, which is an on-line educational platform used for academic purposes. Initially, 926 students completed the survey. However, 40 respondents were discarded due to incomplete questionnaires (related to independent variables: smoking (10), cannabis (20), and alcohol consumption (2)), or were outside the predefined age range (8). This lead to the final inclusion of 886 participants (about 7.4% of all potential participants, n = 11,926), where a minimum of 623 were required for significance ( p < 0.05) based on the sampling population and to ensure a sample size large enough for the results being generalizable to all the undergraduate students from the University of the Balearic Islands [ 18 ].

All the participants were informed of the purpose and demands of the study. Consent to participate in the study was given by agreeing to complete the survey. The protocol was in accordance with the Declaration of Helsinki for research of human participants and was approved by the University of the Balearic Islands Research Ethics Committee (190CER21).

2.2. Data Collection

The following data were collected from participants using the online survey across eight sub-sections to determine caffeine intake (daily amount and sources), the motivations for caffeine intake and association with lifestyle factors such as fruit and vegetable intake, smoking status and alcohol consumption, as well as subjective sleep quality.

Sociodemographic variables. Information on sex, age and course year were collected.

Anthropometrical measurements. Self-reported mass and stature were recorded. Body mass index (BMI) was calculated as mass (kg) divided by stature (m) squared (kg·m −2 ).

Caffeine intake. Habitual daily caffeine intake was measured using a self-reported questionnaire previously developed and used by our group [ 19 ]. The frequency intake of common products containing caffeine was ascertained using the question “How often do you consume…?” with “daily” and “weekly” frequency options provided. Caffeine daily consumption was determined using the caffeine content of each product [ 2 ]. Products included in the questionnaire were coffee preparations, instant coffee, tea and mate, chocolate, cola drinks, and energy beverages. Furthermore, in an open question, participants were asked for any other caffeine source they commonly consumed. Results from a previous study performed in a university population demonstrated that the contribution to total caffeine intake of decaffeinated coffee was negligible (unpublished results). Therefore, this product was not considered in the caffeine intake questionnaire applied in the present study. Coffee intake was estimated from the intake of each coffee preparation contained in the questionnaire. The most common preparations in Spain were considered: espresso, “cortado” (espresso coffee, one serving, with a shot of milk), and “café con leche” (white coffee, or espresso coffee, one serving, with the remaining half of a cup filled with milk or steamed milk). Participants in the study were classified as either caffeine consumers or non-consumers. Participants reporting caffeine intake, any amount, from any source were considered as caffeine consumers.

Motivations for caffeine intake. A Spanish translation of the previously validated Caffeine Motives Questionnaire (CMQ) in participants with a similar age to those of the present study [ 20 ] was used to determine the motivations leading to caffeine consumption among participants. This questionnaire was comprised of 21 items, each one describing a reason for consuming caffeine. Questions were presented with a 5-point Likert scale (1: never ingest caffeine for this reason, 5: always ingest caffeine for this reason). Following the scoring instructions [ 20 ], a global score as well as four factors were calculated as the sum of all or some items. The first factor consisted of six items that reflected cognitive enhancement (alertness, concentration, drowsiness, attention, energy, to stay awake). The second factor was composed of three items that reflected negative affect relief (stress, anxiety, depression). The third factor was composed of nine items that reflected reinforcing effects (headache relief, taste, convenience, relaxation, social, craving, reward, cued craving, mood). The fourth factor was composed of three items that reflected weight control (ingredient in diet pills, powerful diuretic, to lose or control weight).

Alcohol consumption. Frequency of alcohol consumption was ascertained using the question (The Alcohol Use Disorders Identification Test (AUDIT)) “How often do you drink alcoholic beverages?” (Answers: never, once a month or less, 2–4 times a month, 2–3 times per week, and 4 or more times per week). Using this answer, participants were classified as either non-consumers (answered never), or alcohol consumers. For those participants reporting alcohol consumption, the following question was also included: “During a usual consumption day, how many servings of alcohol do you drink?”(Answers: 1–2, 3–4, 5–6, 7–9, 10 or more).

Smoking habit and cannabis consumption. Participants were asked if they smoked (YES/NO) in reference to tobacco consumption and cigarette use and were then classified as non-smokers, ex-smokers, occasional smokers or (daily) smokers, according to the criteria of the 2020 European Health Survey in Spain [ 21 ]. For most of the analyses performed in the present study, this variable was dichotomized into ‘smokers’ (daily and occasional smokers) and ‘non-smokers’ (ex-smokers and non-smokers). Furthermore, participants’ consumption of cannabis (YES/NO) was also ascertained.

Sleep quality. Participants’ self-reported sleep quality was measured using the short form of the MOS (Medical Outcomes Study) Sleep Scale [ 22 ], a six-item Likert-scale form that measures six sleep dimensions including: sleep initiation (time to fall asleep), sleep quantity, maintenance (e.g., middle and early morning awakening), respiratory problems or head ache, perceived adequacy, and somnolence (i.e., sleepiness or drowsiness) with the scale examples ranging from 1—“All of the time” to 5—“None of the time”. A correlation of 0.97 has been determined between the short and the long version [ 23 ]. The MOS Sleep Scale ranges from 6 to 30, and the higher the MOS Sleep Scale value is, the worse the subjective sleep quality is. The continuous score is considered as no cutoff points have been established [ 22 ].

Fruit and vegetable daily intake. The number of daily servings of fruit and vegetables consumed were determined as a marker of diet quality by self-reported average daily consumption with the question “How many servings of fruit/vegetable do you consume daily?” Examples of servings were provided in the survey as follows: 1 average dish of salad, 1 average dish of cooked vegetables, 2 cucumbers, 2 carrots, 1 medium-sized fruit (apple, orange, pear, banana), 1 slice of melon or watermelon, 2–3 small fruits (apricots, plums), or one cup of very small fruit (berries, grape).

2.3. Statistical Analysis

Statistical analysis was carried out using IBM SPSS Statistics 24.0 software (SPSS/IBM, Chicago, IL, USA). Statistical significance was accepted at a p -value below 0.05. To maintain an homogenous number of participants throughout the study and in all the analyses, only participants who provided all the information required were considered in the statistical analysis ( n = 886). All the data were tested for normal distribution (Kolmogorov–Smirnov test). A Student’s t -test for unpaired data or Pearson’s chi-square (χ2) test was used to evaluate differences between sexes. Cohen’s d was determined as a measure of effect size for t -test comparisons. Descriptive analysis was used to report the frequencies and percentages of categorical variables, and the mean and standard deviation (SD) were reported for quantitative variables. The one-way ANOVA with Bonferroni correction was used to compare the intake of caffeine and coffee between participants stratified per smoking habit (daily, occasional, ex- and non-smokers). Eta squared (η 2 ) was determined as a measure of effect size for the ANOVA. Multiple linear regression analysis, using the stepwise procedure, was applied to determine the association between the amount of daily caffeine intake (dependent variable) and independent and control variables (smoking (YES/NO), age, sex, cannabis consumption (YES/NO), alcohol consumption (YES/NO) and daily intake of servings of fruit and vegetables). Multiple regression analysis was also performed in participants distributed per sex. Logistic regression analysis was also used to determine the association between caffeine intake (YES/NO) and all independent variables. The same logistic regression model was used to determine the association between consumption of each caffeine source (YES/NO) and independent variables. Finally, multiple linear regression analysis was applied to determine the association between subjective sleep quality (dependent variable) and caffeine daily intake, with sex, age, smoking (YES/NO), cannabis consumption (YES/NO), alcohol consumption (YES/NO) and daily intake of servings of fruit and vegetables as control variables. Regression models for subjective sleep quality for men and women were also obtained.

3.1. Characteristics of Participants in the Study

Of the participants in the study, 69% were women. This percentage is slightly higher than the proportion of female students in the university (about 59%). Table 1 shows the general characteristics of participants in the study as a whole and stratified by sex. For men, a significantly higher prevalence of cannabis consumption ( p < 0.001) was found. However, the prevalence of alcohol consumption was higher among women ( p = 0.034). Regarding diet, a higher consumption of fruit and vegetable servings were found in women ( p = 0.010). Self-reported sleep quality was poorer in women than in men as indicated by the higher score in the MOS-sleep scale ( p = 0.014).

General characteristics of participants in the study.

Values are the mean ± SD or number of participants (percentage). * p < 0.05 indicates significant differences between men and women, as determined by Student’s t -test for unpaired data or Pearson’s chi-square (χ2). Cohen’s d is provided as a measure of effect size for t -test comparisons.

3.2. Caffeine and Caffeine Sources’ Consumption among Participants in the Study

Average daily caffeine consumption for all students, including non-consumers, was 155.4 mg, with a mean intake of 172.5 mg among caffeine users ( Table 2 ), which corresponds to the caffeine content in two cups of coffee. Women reported a higher caffeine intake than men, both expressed as the absolute intake ( p = 0.007) and the intake per kg of body weight ( p < 0.001). A higher daily intake than recommended (400 mg) [ 2 ], the content of 4–5 cups of coffee, was reported by 77 participants (9.5% of consumers), with similar percentages for men and women (9.0 vs. 9.8%). Caffeine, in any form, was consumed by 91.1% of participants, with higher figures in women than in men ( p = 0.010). Regarding the sources of caffeine, coffee ( p = 0.010), instant coffee ( p = 0.019), and mainly tea and mate ( p < 0.001) were consumed by higher percentages of women than men. However, a higher percentage of men consumed energy drinks ( p < 0.001). Of interest, 128 participants (15.9% of caffeine consumers) indicated chocolate as their only source of caffeine.

Caffeine intake and prevalence of consumption of caffeine and caffeinated products.

Values are the mean ± SD, or number of participants (percentage) consuming caffeine and caffeinated products. # Mean values among caffeine consumers ( n = 807, men n = 243, women n = 564). * p < 0.05 indicates significant differences between men and women, as determined by Student’s t -test for unpaired data or Pearson’s chi-square (χ2). Cohen’s d is provided as a measure of effect size for t -test comparisons.

When the contribution of each caffeine source to total caffeine intake was analyzed ( Table 3 ), coffee was found to be the main source both in men and in women (about half of the total caffeine intake). The contribution of tea and mate was about twice as high in women than in men ( p < 0.001). On the other hand, the contribution of energy drinks was about five times higher in men than in women ( p < 0.001).

Sources of caffeine intake among participants in the study.

Values are expressed as means ± S.D. and represent the caffeine contribution in percentage of each source with respect to total caffeine intake. * p < 0.05 indicates significant differences between men and women, as determined by Student’s t -test for unpaired data. Cohen’s d is provided as a measure of effect size.

3.3. Analysis of the Variabales Associated with Caffeine and Caffeine Sources’ Consumption

Linear regression was used to examine daily caffeine intake (mg·day −1 ). Logistic regression was applied to examine whether participants consumed caffeine and caffeine sources or not. Table 4 shows the results of the multivariable regression analysis for daily caffeine intake (dependent variable). Smoking was found as the main predictor for a higher daily intake of caffeine (change in R 2 0.052, p < 0.001). A higher fruit and vegetable intake ( p < 0.001), alcohol consumption ( p < 0.001), cannabis consumption ( p = 0.001), female sex ( p = 0.014) and older age ( p = 0.039) were also significantly associated with a higher caffeine intake.

Multivariate regression analysis for daily caffeine intake (mg·day −1 ).

Model: p < 0.001 (ANOVA). B: regression coefficient; β: standardized beta coefficient. The positive coefficients for smoking, alcohol and cannabis indicate higher values for caffeine intake in consumers of these substances than in non-consumers. The positive coefficient for sex indicates higher values for caffeine intake in women than in men. * p < 0.05 indicates significant predictors or R 2 changes.

Multivariate linear regression models for daily caffeine intake were also obtained for men ( Table S1 ) and women ( Table S2 ). Smoking remained as the main predictor in men and women, with similar standardized coefficients (0.227 vs. 0.153, respectively). In women, age became a non-significant predictor ( p = 0.604), while similar coefficient values for fruit and vegetable intake and smoking were observed (0.166 vs. 0.153).

Table 5 shows results of the logistic regression analysis for caffeine intake (YES/NO). This analysis revealed that caffeine consumers were more likely to be women ( p = 0.022), smokers ( p = 0.048) and alcohol consumers ( p = 0.002).

Logistic regression analysis for caffeine intake (consumers and non-consumers).

Reference: non-consumers of caffeine; * p < 0.05 indicates significant odds ratios (OR).

The logistic regression analysis was also applied to the consumption of caffeine sources considered: coffee, instant coffee, tea and mate, chocolate, cola drinks, and energy drinks. All variables included in the analysis, except cannabis consumption, were significantly associated with consuming coffee ( Table S3 ). However, consuming instant coffee was only associated to female sex. Tea and mate intake was associated with female sex and with a higher intake of fruit and vegetables ( Table S4 ). Cola drinks’ intake was found to be associated with smoking and with alcohol consumption ( Table S5 ). Energy drinks’ intake was associated with male sex and being a smoker.

3.4. Caffeine Consumption Stratified per Smoking Habits

Significant differences ( p < 0.001) were found for daily caffeine intake between participants in the study distributed by the smoking categories ( Table 6 ). No differences were observed between non-smokers and ex-smokers ( p = 1.00), neither between occasional and habitual smokers ( p = 1.00). A higher caffeine intake was observed in habitual smokers than in ex- ( p = 0.030) and non-smokers ( p < 0.001). A similar picture was observed for coffee intake (expressed as the number of coffee servings consumed daily), with significant differences between categories ( p < 0.001) and higher values in smokers than in non-smokers.

Caffeine and coffee consumption in participants distributed per smoking habit.

Values are expressed as means ± S.D. * p < 0.05 Indicates significant differences (ANOVA one-way test). η 2 value is provided as a measure of effect size.

Table 7 shows the pattern of caffeine and caffeine sources in non-smokers and smokers. There were significantly higher values for daily caffeine ( p < 0.001) and coffee ( p < 0.001) intake in smokers than in non-smokers. Furthermore, the prevalence of consumption of caffeine ( p = 0.006), coffee ( p < 0.001), cola drinks ( p < 0.001), and energy drinks ( p < 0.001) were higher among smokers.

Caffeine intake and prevalence of consumption of caffeine and caffeinated products in smoker and non-smoker participants.

Values are the mean ± SD, or number of participants (percentage) consuming caffeine and caffeinated products. p < 0.05 * indicates significant differences between smokers and non-smokers, as determined by Student’s t -test for unpaired data or Pearson’s chi-square (χ2). Cohen’s d is provided as a measure of effect size for t -test comparisons.

3.5. Multivariate Regression Analysis for Subjective Sleep Quality

Table 8 shows results of the regression analysis for sleep quality as a dependent variable, with higher values of the scale being associated with a worse subjective sleep quality. Caffeine intake was found as the main predictor, with a negative effect on sleep quality ( p < 0.001). Furthermore, a higher daily intake of fruit and vegetables ( p = 0.001) and male sex ( p = 0.030) were associated with better sleep quality. No associations with sleep quality were found for age, smoking and cannabis consumption.

Multivariate regression analysis for subjective sleep quality.

Regression model: p < 0.001 (ANOVA). B: regression coefficient; β: standardized beta coefficient. Caffeine: caffeine intake (mg/day); fruit/vegetables: servings of daily fruit and vegetables intake. The positive coefficient for sex indicates higher values of MOS Sleep in women than in men. * p < 0.05 indicates significant predictors or R 2 changes.

Multivariate linear regression models for subjective sleep quality were also obtained for men ( Table S6 ) and women ( Table S7 ). Caffeine and fruit/vegetable intake remained as the only significant predictors for subjective sleep quality in men and women.

3.6. Motivations for Caffeine Consumption among Participants in the Study

No differences between men and women were found for the global CMQ score ( Table 9 ). Regarding the four factors considered, higher values for women than for men were found for Factor 4 ( p = 0.016), which included motives related to weight control. Considering the factors’ score ranges (lowest and highest possible score), and the participants’ scores, the most relevant factor was Factor 1 (cognitive enhancement). While this Factor 1 reached about 39% of its highest score, the other factors reached between 3% and 15% of the score range ( Table S8 ).

Results of the Caffeine Motives Questionnaire.

CMQ: Caffeine Motives Questionnaire. * p < 0.05 Indicates significant differences between men and women, as determined by Student’s t -test for unpaired data. Cohen’s d is provided as a measure of effect size.

When the items included in the questionnaire were considered ( Table S9 ), those with the highest scores were related to the “like of the taste of caffeinated beverages” (3.32 ± 1.41) and to “stay awake” (3.23 ± 1.46). Regarding differences between men and women, significantly higher values in women were found for the reasons “to feel more alert” ( p = 0.011), “as a reward to myself for completing a task” ( p = 0.008), and “because it is a powerful diuretic” ( p = 0.022). On the other hand, a higher value in men was observed for the reason “because it’s convenient to drink caffeinated beverages” ( p = 0.028).

4. Discussion

The aim of the present study was to determine the pattern of caffeine and caffeine sources’ consumption and the motivations for caffeine consumption among undergraduate students from the University of the Balearic Islands. The main results of the present study are the differences found between men and women, and also between smokers and non-smokers, regarding the pattern of caffeine consumption. Undergraduate university female students reported a higher daily consumption of caffeine, with higher prevalence of coffee and tea intake. On the other hand, men reported a higher prevalence of energy drink consumption. Higher caffeine consumption was associated with habits such as smoking and alcohol consumption, as well as with a higher intake of fruit and vegetables. Caffeine intake was also associated with poorer subjective sleep quality.

Caffeine was consumed by 91.1% of participants in the present study. This value was very similar to studies performed in university or college students from the US [ 6 ] or Netherlands [ 5 ]. However, it should be noted that in the present study, about 16% of consumers reported caffeine intake only from chocolate, a caffeine source that was not always considered in previous studies. In spite of this observation, the average daily caffeine consumption observed was similar to that found in previous studies focused on university students from different locations such as the US [ 6 ], New Zealand [ 24 ], Netherlands [ 5 ] and the European surveys examining similar age groups [ 2 ]. Furthermore, measured daily caffeine intake was also similar to a previous study performed by our research group in a cohort of slightly older participants from the same university (155.4 mg in the present vs. 164.3 mg in the previous study) [ 19 ]. Among caffeine consumers, 9.5% of participants in the present study reported daily caffeine intakes higher than the recommended amount (400 mg) [ 2 ]. This percentage is slightly lower than that recently found in a similar population from New Zealand (15%) [ 4 ], where the prevalence of caffeine consumption was about 99%, but this was higher than values usually found in even older populations [ 2 , 25 ]. Due to the potential negative effects of excessive caffeine intake, future studies should pay attention on these high consumers to prevent potential public health issues [ 4 ].

In the present study, prevalence of caffeine consumption observed among women was higher than in men [ 6 ], with also a higher daily caffeine intake per kg of body weight [ 4 ]. It has been reported that caffeine in women is metabolized 20–30% faster than in males [ 26 ]. Therefore, women could be able to consume relatively higher amounts of caffeine without experiencing more intense or prolonged effects [ 4 ].

A weak association was found between caffeine consumption and age. This association has been previously reported in college students [ 6 ], and becomes stronger when a wider age range is considered [ 3 ]. Reasons for this association are not well-understood, and it has been mainly attributed to increasing demands over the lifespan rather than genetic or physiological reasons [ 3 ].

In agreement with previous studies performed in similar populations, the source that most contributed to total caffeine intake was coffee [ 5 , 6 , 27 ], with a higher prevalence of coffee consumption in women than in men [ 6 ]. The current study also noted a lower consumption of tea compared with studies performed in other countries [ 4 , 6 ], which may be due to cultural differences in drink preferences. The prevalence of tea (and mate) intake, as well as the contribution of tea to total caffeine intake, was, however, higher in women than in men, which agrees with previous observations in college students [ 6 ]. On the other hand, as has been previously observed [ 6 , 28 ], higher values of consumption and contribution to total caffeine intake for energy drinks were found in men. In spite of the increasing popularity [ 29 ], the highest consumption commonly observed among young people [ 25 , 27 , 30 ], including university students [ 6 , 28 ], energy drinks accounted for less than 4% of the total caffeine consumption, resulting in the lowest contributor among caffeine sources considered. Furthermore, prevalence of consumption (10.7%) was lower than in previous studies, with values as high as 23% [ 29 ] or one-third of college students consuming at least one energy drink over the previous month [ 29 ]. Finally, regarding caffeine sources, the high contribution of chocolate, as the second main source, should be highlighted. This is of special interest because similar previous studies focused on university students considered only caffeinated beverages as caffeine sources [ 5 , 6 , 12 ]. Therefore, results from the present study provides novel insight into the main caffeine sources in university students.

Previous studies have reported higher caffeine intakes among smokers than non-smokers [ 6 , 31 ]. In agreement with these observations, results from both the multivariate and the logistic regression analyses showed an association between caffeine intake and smoking. Furthermore, results from the present study suggest that this association depends on the caffeine source, as the prevalence of coffee, cola and energy drink consumption was found to be higher among smokers, while no differences were observed for the remaining caffeine sources considered. These results are similar to previous studies showing that smokers consumed more coffee [ 6 , 12 ], soda [ 6 ] and energy drinks [ 6 ] than non-smokers. Physiological, cognitive and environmental factors may all contribute to the association between smoking and caffeine intake. Smoking increases the rate of caffeine metabolism [ 9 , 10 ]; as a consequence, smokers must consume caffeine more frequently than non-smokers to maintain similar effects. Other factors, such as stress, could have similar effects on the use of both caffeine and nicotine leading to increased use of both [ 32 ]. A previous study performed in a young population showed that nearly 50% of participants reported increasing caffeine consumption when under stress [ 33 ].

Higher caffeine intake has been also associated with alcohol consumption, a result commonly described in the literature [ 3 ]. This association has been attributed, at least in part, to the sharply increased combined use of caffeine and alcohol, with studies suggest that such combined use may increase the rate of alcohol-related injury [ 34 ]. In agreement with this suggestion, in the present study a significant association was found for alcohol and cola drinks consumption. Caffeine consumption was also associated to cannabis consumption. The main reason for this association remains unknown, and cannabis use has been more linked to alcohol and tobacco consumption [ 35 ]. Biological effects, such as cross-sensitization and activation of the reward system, or because the use of one substance influences the metabolism or enhances the effect of another substance cannot be discarded [ 35 ].

On the other hand, a positive association was found in the current study between caffeine intake and servings of fruit and vegetables. This result is contrary to those found in previous studies reporting associations between caffeine, or coffee intake, and negative characteristics of the diet, including low vegetable intake [ 36 ]. However, it should be considered that these studies were performed in older populations, with coffee consumers reporting higher prevalence of hypercholesterolemia and other conditions that could involve dietary limitations, while similar studies focused on caffeine consumption in university or college students or in younger populations did not consider characteristics of the diet [ 4 , 5 , 6 , 12 ].

Examining factors associated with subjective sleep quality in university students is essential, as it has been suggested that risk factors for poor sleep quality in young adulthood are likely to differ from risk factors in adolescence or adulthood [ 37 ]. Increased consumption of caffeinated beverages has been associated with poorer subjective sleep quality in university students [ 12 , 38 , 39 ]. In agreement with these observations, in the present study, caffeine intake was found as the main predictor of poorer subjective sleep quality. Proper sleep homeostasis has been related to effects of high adenosine concentrations during time awake, and their dissipation during the sleep episode [ 40 ]. Caffeine, due to its adenosine receptor antagonistic nature [ 41 ], could interfere with this mechanism, leading to sleep disruptions and worse sleep characteristics. Furthermore, it has been reported that caffeine may inhibit adenosine from melatonin secretion [ 42 ]. Melatonin has been considered as a key neurohormone in the regulation of the sleep-awake cycle in humans, with levels starting to rise about two hours prior to habitual bedtime [ 43 ]. Therefore, caffeine intake could modify the common circadian rhythm of melatonin, leading to sleep disturbances. Previous studies also reported worse values for different parameters related to sleep quality in female than in male students [ 16 , 17 ]. This is similar to the findings of the present study, showing worse subjective sleep quality in women. Poorer sleep quality in female than in male university students has been related to the lower stress levels in male students [ 44 , 45 ]. For instance, personal and academic stress have been reported to negatively affect sleep quality in college students [ 44 ]. However, it should be considered that, in addition to the aforementioned parameters, there may be other factors that significantly affect sleep quality such as stress, electronic device usage, physical activity, and fast-food consumption [ 12 ]

In the present study, subjective sleep quality was found to be inversely associated with fruit and vegetable consumption. In university and college students, an inverse association between fruit and vegetable consumption with poor sleep quality and restless sleep was reported [ 46 ]. It has been suggested that the positive effects of fruit and vegetable intake on sleep may be due to the high content of melatonin and serotonin [ 47 ], but also to the high amount of antioxidants, which could play a role in improving sleep quality [ 48 , 49 ]. On the other hand, poorer sleep quality is associated with higher intake of energy-dense foods but lower intake of fruit and vegetables [ 49 ]. Furthermore, sleep disruption could modify the pattern of appetite-related hormones, leading to an increase of energy-dense foods and a decrease in fruit and vegetable consumption [ 50 ]. Therefore, the relationship between fruit and vegetable intake and sleep parameters has been suggested to be bidirectional [ 51 ]. Taking into account the nature of this relationship, public health interventions, or approaches from university health services, should be addressed to increase fruit and vegetable intake, but also to improve sleep hygiene [ 49 ].

Factors considered in the present study (sex, age, smoking, alcohol and cannabis consumption, and diet quality) could explain only a limited fraction of all inter-individual variation in caffeine consumption. To complete this picture, participants’ reasons to consume caffeine were also ascertained. Such reasons related to staying awake, to avoid drowsiness, to feel more alert, to enjoy taste, and to help in concentration, were among those with the highest scores, being, some of them of interest for university students to enhance their academic performance. These results were very similar to those reported in college students from five universities in the US [ 6 ], in which most participants reported using caffeine-containing products to enhance some aspect of mood or performance, mainly to feel more awake and alert, and to enjoy the taste, as well as to improve concentration. These observations agree with results from research studies reporting positive effects of caffeine intake on mood and cognitive performance [ 52 , 53 , 54 ]. However, it was also shown that if the caffeine dose was too high (500 mg), the arousal levels of the participants were overstimulated, and continuous attention task performance began to decline [ 55 ]. It is noteworthy that, within the low scores observed in the present study, higher values in women were found for the factor related to weight control (Factor 4). Analyzing scores of each item included in this factor, the difference can be mainly attributed to the use of caffeine as a diuretic, but also to help lose or control body weight. A previous study showed that caffeine consumption was significantly associated with weight loss [ 6 ], but differences between sexes were not analyzed.

This study presents some limitations that should be acknowledged. In addition to the limitations due to the observational nature, the current study was limited to cross-sectional self-reported data from students belonging to a single Balearic Spanish university. Furthermore, the different questionnaires used in the present and in previous studies to record caffeine intake could have influenced comparisons with previous studies. Motivations for caffeine consumption were ascertained in general rather than for each caffeine containing product, which could have provided valuable information, because a previous study performed in university students suggested that the main reasons for consuming each product could be different [ 12 ]. Regarding sleep quality, factors that could affect sleep such as noise, stress, artificial light or electronic media usage were not considered in the present study. Furthermore, specific sociodemographic variables such as socioeconomic status were not assessed. The survey was performed when some restrictions due to COVID-19, for example limited opening times of cafes, bars or restaurants, were still in effect, which could have affected the answers of participants. Finally, data collection took place at the beginning of the second term within the academic calendar, which supposes, in general, a non-stressful academic period. It could be expected that patterns determined in the present study change in more demanding academic periods.

5. Conclusions

Women and smokers of university undergraduate students reported higher caffeine intakes. The faster metabolism of caffeine in both women and smokers could be the main reason leading to this higher intake. Coffee was found as the main caffeine contributor, with higher contributions of tea in women and energy drinks in men. Caffeine intake was also found to be associated to poor subjective sleep quality. Main reasons for caffeine intake among university students were related to increased mood and alertness, together with enjoying the taste. Universities should consider the implementation of health campaigns and educational programs to educate students of the risks of high caffeine consumption and poor sleep quality to physical health and academic performance. Associations reported in the present study could allow implementing appropriate educational strategies to address behaviors in combination such as smoking, alcohol consumption and excessive caffeine intake, all of which are linked to an increased risk of poor health. Furthermore, results obtained could help universities and health professionals working with students to increase sleep quality and, potentially, academic performance.

Acknowledgments

The authors would like to thank all participants in the study as well as all the members of the University of the Balearic Islands academic staff who assist in the distribution of the survey among students.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/nu14081661/s1 , Table S1. Multivariate regression analysis for daily caffeine intake (mg·day −1 ) in men; Table S2. Multivariate regression analysis for daily caffeine intake (mg·day −1 ) in women; Table S3. Logistic regression for coffee and instant coffee intake; Table S4. Logistic regression for tea/mate and chocolate intake; Table S5. Logistic regression for cola and energy drinks intake; Table S6. Multivariate regression analysis for subjective sleep quality in men; Table S7. Multivariate regression analysis for subjective sleep quality in women; Table S8. Results of the Caffeine Motives Questionnaire (%); Table S9. Motivations for caffeine consumption.

Author Contributions

Conceptualization, P.T.; methodology, P.T., S.M., A.R.-S. and L.R.; formal analysis, P.T. and H.J.M.; investigation, L.R., S.M., A.R.-S. and P.T.; resources, P.T. and S.M., data curation, A.R.-S. and P.T.; writing—original draft preparation, A.R.-S.; writing—review and editing, P.T., L.R., H.J.M. and S.M.; visualization, A.R.-S.; supervision, P.T. and S.M.; project Administration, P.T. and S.M. All authors have read and agreed to the published version of the manuscript.

This research received no external funding.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki, and approved by the Research Ethics Committee of the University of the Balearic Islands (protocol code 190CER21, date of approval 1st February 2021) for studies involving humans.

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

Conflicts of interest.

The authors declare no conflict of interest.

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