Improving College Exam Performance with L-theanine and Caffeine

By Henry GongSciences, Cycle 5, 2014



Students who experience test anxiety struggle to maintain high grades in their classes even if they have studied the material. Current treatment options for test anxiety are limited. This paper proposes the potential of caffeine and L-theanine as a treatment option. L-theanine is a kind of nonessential amino acid found readily in tea, and research has shown that it has the ability to lower the user’s stress levels and increase relaxation. Studies have shown that the combination of L-theanine with caffeine can significantly lower symptoms of test anxiety.


Test anxiety limits the maximum exam performance of certain students despite the amount of work they put into improving their understanding of academic material. With pounding hearts and distressed minds, students with test anxiety fare poorly academically compared to their non-anxious peers. The apparent futility of studying in the face of hampered recall ability and impaired problem solving during an exam can lead to further academic decline, lowered self-esteem, and learned helplessness, a behavior in which the subject is forced to endure a painful experience because he or she believes the stimulus is inescapable.1 To reduce test anxiety, thus improving academic performance and health for many college students, this project proposes the easily distributed and practical treatment of the combination of caffeine and L-theanine. This paper will outline the effects of test anxiety on student exam performance, the potential of caffeine and L-theanine as a treatment option, and the current treatments for test anxiety.

Multiple scales have been constructed to measure and research test anxiety, including the Cassady and Johnson Cognitive Test Anxiety Scale. This scale was developed to identify and measure cognitive factors correlated with high test anxiety, such as distractibility and emotionality, with a self-report inventory. Over the course of an extensive pilot test, in which hundreds of students’ test anxieties and test scores were measured, high test anxiety on the scale was correlated with significantly decreased test performance. The Cassady and Johnson study demonstrated that test anxiety could cause afflicted students to perform upwards of 10% lower than non-anxious students at similar achievement levels.1 Students with higher test anxiety display an acute stress response during exams as the sympathetic nervous system activates and releases stress hormones, such as cortisol and epinephrine. According to the Anxiety and Depression Association of America, test anxiety can cause a number of physiological symptoms, such as sweating, rapid heart rate, and panic attacks. In addition, test anxiety can cause negative cognitive effects, including difficulty concentrating and negative thinking, along with disruptive emotional responses, such as anger and helplessness.2 These symptoms detract from exam performance by preventing students from focusing on their current tasks. Poor performance on exams, in spite of extensive studying or preparation, can lead to reduced student grades, motivation, and self-esteem.3 As a common source of stress in students, test anxiety can drastically reduce the health of afflicted individuals due to the detrimental effects that stress causes on the immune system and other bodily functions. Reducing test anxiety can therefore help improve self-esteem, grades, and health in students.3 At present, the main methods used to treat test anxiety consist of cognitive behavioral therapy and the prescription of anti-anxiety drugs, both of which have disadvantages for many students.

L-theanine is a type of nonessential amino acid found almost exclusively in tea.7 It is easily absorbed into the bloodstream when consumed, and can cross the blood-brain barrier through the L-system. Due to its similarity to glutamate, another amino acid and a principal excitatory neurotransmitter, the incorporation of theanine in the brain may antagonize glutamate and reduce its release.4 By antagonizing the release of glutamate, L-theanine may cause a calming effect on users. The exact pharmacology of L-theanine is not known for certain, however, though it has been suggested that L-theanine acts as a glutamate transporter and inhibits its reuptake, thereby reducing levels of excitatory glutamate available to neurons.4, 5 L-theanine has also been reported to increase levels of GABA, a principal inhibitory neurotransmitter and a product of glutamate. The increased levels of GABA may be partially responsible for L-theanine’s anxiolytic effects. Decreased levels of norepinephrine, a well-known stress hormone, have also been reported under L-theanine supplementation.5, 7 L-theanine consumption has also been reported to increase concentrations of dopamine and serotonin, neurotransmitters that stimulate a sense of reward and well-being, in various parts of the brain. As with the antagonism of glutamate, L-theanine’s mechanism of action in boosting these neurotransmitters are poorly understood.6 The release of dopamine and serotonin, as ‘reward’ chemicals, may help people with test anxiety by possibly associating exams with a sense of wellness.

L-theanine and caffeine together may serve as suitable alternative treatments for test anxiety. Research on L-theanine has shown possible ability to relax users and decrease psychological stress levels.7 An experiment conducted by researchers Kimura, Ozeki, Juneja, and Ohira at Nagoya University measured the effects of L-theanine dosing on subjective stress and cardiovascular function in human participants. In the experiment, mental arithmetic served as a stressor, and psychological stress responses were measured with psychometric tests. The group using 200 mg of L-theanine reported lower levels of subjective stress as measured by an anxiety Visual Analogue Scale and a State-Trait Anxiety Inventory (STAI).8 The VAS is a scale used to define characteristics that cannot be measured directly by pinpointing them on a continuum, such as a scale from 1 to 10. The STAI is a self-report inventory that measures state anxiety, the intensity of an individual’s reaction to stress, and trait anxiety, an individual’s susceptibility to stress. A decreased physical stress response was also reported via cardiovascular monitoring.9 A decreased stress response should help alleviate the physical symptoms of test anxiety, such as pounding heart and muscle tension, while decreased subjective stress should allow for better mental processing during exams. In another study that examined the stress of fifth-year pharmacy students, students were given either 200 mg of L-theanine or placebo and their stress levels were measured. Students taking L-theanine had lower levels of subjective stress and decreased anxiety as measured with the STAI, compared to placebo.4 The effect of pharmacy exams on Japanese graduate students could be comparable to the effect that exams have on American undergraduate students. This study assessed an additional metric, salivary alpha-amylase (sAA) activity, which is an indicator of physical stress.

L-theanine can readily alleviate symptoms of somatic stress, perhaps to a level on par with prescription anxiolytics. As previously mentioned, Japanese graduate pharmacy students who took 200 mg of L-theanine had decreased levels of subjective stress compared to placebo. The decrease in cognitive stress occurred in conjunction with decreased sAA activity. Salivary alpha-amylase is a salivary digestive enzyme that appears with noradrenaline when the sympathetic nervous system is triggered in response to increased levels of stress.4 The decreased levels of sAA activity in this study suggest an attenuation of somatic stress resulting from L-theanine supplementation. The experiment of Kimura et al. described on the previous page conducted cardiovascular monitoring in addition to determining mental stress during the arithmetic task stressor and measured heart rate and heart rate variability. Increased cardiovascular activity in the absence of physical exercise can indicate a stress response. During the arithmetic task stressor and immediately following, the group using L-theanine had lower heart rates and variability than the control group.8 L-theanine appears to have a mild but significant effect in reducing somatic stress responses, which can help remove some of the most overt symptoms of anxiety. Hence, L-theanine, taken alone, may decrease levels of test anxiety for most users and thereby improve overall exam performance. L-theanine does have limits to its anxiolytic abilities, however, as evidenced by another study comparing the amino acid’s anxiolytic effects to alprazolam, a benzodiazepine. The study created a sense of anticipatory anxiety by administering random electric shocks to subjects. While L-theanine had significant calming effects at baseline levels (without shock) compared to alprazolam, neither drug produced significant anxiolytic effects when electric shock was randomly administered.5 The electric shock proved to be too strong of a stressor for either drug.

L-theanine, which has anxiolytic effects when taken alone, can be combined with caffeine to further enhance cognition while still reducing anxiety. A number of studies have detailed the fatigue-reducing, reaction-speeding, mood-improving, and perception-enhancing effects of caffeine.7 These positive effects, however, are balanced by possible negative effects, such as jitteriness, anxiety, and a later drop in energy levels. L-theanine may interact synergistically with caffeine to maintain the focusing effects of caffeine while decreasing its anxiety or jitter-inducing effects during cognitively demanding tasks.10, 11 In one particular study, the attention and mood of participants was measured as they completed a variety of cognitively demanding tasks after they were administered a dose of caffeine. Another group was also dosed with L-theanine, while one more group received placebo. The group receiving both L-theanine and caffeine displayed quicker reaction speed and improved mood compared to the other groups.12 Another study assessed participants’ task accuracy and attention as they completed different sets of tasks. One group was dosed with a combination of caffeine and L-theanine, and the other received a placebo. The test reported an increase in attention, accuracy, especially when switching tasks, and decreased subjective levels of fatigue when L-theanine and caffeine were taken in combination compared to placebo.12 Such an effect may counteract the mentally distracting effects of test anxiety and improve overall test performance. These studies help demonstrate the additional cognitive benefits of L-theanine and caffeine taken together over a single drug.7

Caffeine and L-theanine may enhance cognitive function and decrease stress responses to a variety of stressors. These effects may make them suitable treatments for test anxiety. Additionally, the two drugs are affordable and generally nontoxic. In past research, neither drug appears to have high toxicity or significant negative side effects at common dosages of up to 200mg of either.13 In a toxicology experiment on rats, ingestion of 4000 mg/kg of L-theanine did not cause any negative side effects. The FDA classifies caffeine, the most consumed drug in the world, as generally safe due to the relatively high lethal dose of 10,000 mg, which is far beyond the average 100mg in a cup of coffee.13 These two drugs are generally safe for mass distribution, which adds to their potential use in treating test anxiety. The combination of the two may be able to improve mood, attention, reaction time, and cognitive performance, and reduce anxiety and fatigue in the majority of users. While various studies on the two drugs have detailed their effects on cognitive and biological functions during testing, no research appears to have focused specifically on the ability of the drugs to improve performance on academic tests or their ability to quantitatively reduce test anxiety. More research should be conducted in this area to determine the drugs’ applicability as a treatment for test anxiety.

In order to test the efficacy of any combination in reducing test anxiety and thereby increasing test performance, I propose an experiment employing groups of college students who have been tested and determined to have debilitating test anxiety according to the Cassady and Johnson Cognitive Test Anxiety Scale. In a double-blind study, control groups totaling 5 non-anxious and 5 anxious students will receive placebo. Another group of around 30 students, divided into highly anxious, moderately anxious, and non-anxious groups, will receive L-theanine, caffeine, or the combination as they complete a general knowledge standardized exam, such as the SAT, that is unaffected by the subjects’ focus of study in college. In other studies, the most common dosage of combined caffeine and L-theanine seems to be 100 mg of caffeine and 50 mg of L-theanine, although an optimal dosage for cognitive benefit is relatively unstudied.4 When L-theanine is taken alone, 200 mg seems common. Participants in this study will receive varying dosages and ratios of the two drugs in an attempt to determine an optimal dosage. With regard to test anxiety, a dose of L-theanine by itself may improve test performance the most. Some form of reward or punishment may be offered with the test to simulate academic exam conditions. Upon conclusion of the study, data received will be analyzed to determine correlations between dosages administered and test anxiety. Lowered test anxiety should correlate with higher test performance. The effects and costs of using caffeine and L-theanine to treat test anxiety can then be compared to current treatments for test anxiety, cognitive behavioral therapy, and anti-anxiety drugs, to determine if the combination can serve as an effective alternative treatment.

Debilitating test anxiety is mainly treated by cognitive behavioral therapy, or through the prescription of anti-anxiety drugs, i.e., tranquilizers.2 Approaches of cognitive behavioral therapy that have reportedly been successful in combatting test anxiety include systematic desensitization, positive self-instruction, cognitive restructuring, and attention training.3 These approaches involve teaching patients to ignore fearful stimuli. Systematic desensitization, for example, calls for the conditioning of a patient to cope with stressful stimuli. Cognitive restructuring and attention training involve altering the thinking process to recognize and overcome irrational fears or to focus on thoughts besides the source of the anxiety. These approaches often require weekly small-group sessions over the course of a few months, with each session lasting about an hour.16 Cognitive behavioral therapy may not be effective for all students, and students with high test anxiety may also turn to prescription anti-anxiety drugs.

The drugs used for test anxiety include anxiolytics, also known as minor tranquilizers, which generally decrease psychological anxiety by acting as depressants and decreasing uptake of neurotransmitters in the central nervous system. Benzodiazepines are a commonly prescribed anxiolytic for many anxiety disorders. The mechanism of action of these drugs may cause numerous negative side effects, including deterioration of motor skills, memory impairment, tolerance, dependence, increased anxiety, and even death. The risk of these side effects increases if anxiolytics are taken with other depressant drugs, such as anticonvulsants or antihistamines, which many students must take for other conditions.2, 14 Another class of drugs used for anxiety are beta blockers, which can combat the somatic effects of stress through inhibition of beta receptors, cells which help activate the sympathetic nervous system and control stress responses. Like anxiolytics, beta blockers can cause a wide range of adverse effects, ranging from insomnia to heart failure. The extensive action of beta blockers on the sympathetic nervous system results in depressive effects that can harm individuals, especially during periods of excitement when the sympathetic nervous system is normally activated.15 As mentioned earlier, L-theanine was found to have similar efficacy to Alprazolam, a common benzodiazepine, in treating low anticipatory anxiety simulated by impending electrical shock on human subjects.5 Although both drugs were relatively ineffective in alleviating anticipatory anxiety, the study helps demonstrate that L-theanine can have comparable effects to benzodiazepines and other prescription drugs in many cases. The mechanism of action of L-theanine appears similar to prescription anxiolytic drugs; however, L-theanine has not been shown to have significant toxicity at any known dosage. Lacking the side effects of prescription anxiolytics while still responding well to mental stressors, L-theanine appears to be a suitable treatment for many students who suffer mild to moderate test anxiety.

Cognitive behavioral therapy and drug prescription can effectively treat debilitating test anxiety, especially when used concurrently. Cognitive behavioral therapy can be an extremely time consuming and costly process, which may deter many students seeking treatment for test anxiety. Additionally, psychological therapy may carry a negative stigma for many students.16 Likewise, drug prescriptions can be costly, viewed negatively, and carry a range of side effects which can further reduce academic performance or pose significant dangers to users. More research should be put into alternative treatments for test anxiety, such as caffeine and L-theanine. Many students already commonly consume these two drugs with no ill effects, as both are present in common varieties of tea and widely available for sale in various forms. Neither drug has been found to result in significant harmful long-term side effects in most consumers, unlike many anti-anxiety drugs. Currently, research has already determined a wide range of positive effects, which are not restricted to mitigating test anxiety and include cognitive enhancement, which may benefit students who consume the two drugs. If the combination can serve as a viable treatment for test anxiety, then it can offer a practical alternative for many students who will be able to improve their academic performance easily, without resorting to therapy or prescription drugs. By decreasing test anxiety, the general health of a large group of students can be improved.

Although tea is the main natural source of L-theanine, drinking large amounts of tea may not be a practical means of obtaining the amino acid. A cup of green tea contains only around 10 mg of the substance, and a cup of black tea contains around 30 mg.17 While these dosages may possess mild effects that account for some of the subjective differences between tea and coffee, which contains caffeine but lacks L-theanine, they are far below the 100-200 mg dosages used in most experiments involving L-theanine to achieve anxiolytic effects. Fortunately, both caffeine and L-theanine are easily obtainable and inexpensive. L-theanine can be most effectively ingested in its pure and tasteless powder form, which is available from well-known online retailers as well as specialty health stores. The powder dissolves readily in hot liquid, but can be stirred into cold water if necessary. Appreciable amounts of caffeine can be obtained from coffee or tea, which L-theanine powder can be mixed into. Concentrated caffeine is also available for purchase in pill or powder form from many supermarkets or online retailers. The effects of caffeine and L-theanine, consisting of mental clarity, energy, and relaxation, should appear half an hour after ingestion.

While L-theanine has been shown to reduce anxiety in a number of experiments, it is not clear what the limits of the drug’s anxiolytic effects are. L-theanine proved relatively ineffective in decreased stress from anticipatory anxiety brought on by electric shock.5 The drug was quite effective, however, in reducing subjective and physical stress resulting from mental tasks. An avenue of further study for L-theanine could involve its use as an anxiolytic for various applications, such as test anxiety, to delineate the practical uses of the drug. Further research could also study the long-term health effects of L-theanine to determine if it can boost subject health by reducing stress in the long term. A better understanding of the pharmacology of L-theanine could also be useful in bolstering its effects. In a study of rats, L-theanine acted synergistically with midazolam, a benzodiazepine, and significantly reduced fine motor movements compared to midazolam alone.6 Similar to its interaction with caffeine, L-theanine could have synergistic interactions with a variety of other drugs and boost their effectiveness or mitigate their drawbacks. The proposed mechanism of action of L-theanine – Glutamate inhibition and GABA facilitation – are similar to those of depressants; however, L-theanine is not known to have any side effects. Further research on the pharmacology of L-theanine could be useful in developing better treatments for anxiety.



1. Cassady J, Johnson R. Cognitive test anxiety and academic performance. Contemporary Educational Psychology. 2002;27(2):270-295.

2. Test Anxiety [Internet]. Silver Spring (MD): Anxiety and Depression Association of America [cited 2014 Mar 1]. Available from:

3. Hembree R. Correlates, causes, effects, and treatment of test anxiety. Review of Educational Research. 1988;58(1):47-77.

4. Unno K, Tanida N, Ishii N, Yamamoto H, Iguchi K, Hoshino M, Takeda A, Ozawa H, Okhubo T, Juneja L, et al. Anti-stress effect of theanine on students during pharmacy practice: Positive correlation among salivary α-amylase activity, trait anxiety and subjective stress. Pharmacology Biochemistry and Behavior. 2013;111:128-135.

5. Lu K, Gray M, Oliver C, Liley D, Harrison B, Bartholomeusz C, Phan K, Nathan P. The acute effects of L-theanine in comparison with alprazolam on anticipatory anxiety in humans. Human Psychopharmacology: Clinical and Experimental. 2004;19(7):457-465.

6. Heese T, Jenkinson J, Love C, Milam R, Perkins L, Adams C, McCall S, Ceremuga T. Anxiolytic effects of L-theanine – a component of green tea – when combined with midazolam in the male Sprague-Dawley rat. American Association of Nurse Anesthetists Journal. 2009;77(6):445-449.

7. Bryan J. Psychological effects of dietary components of tea: caffeine and L-theanine. Nutrition Review. 2008;66(2):82-90.

8. Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biological Psychology. 2007;74(1):39-45.

9. Yuka N, Tetsumi S, Mihoko K, Kiyoshi K, Kazuyoshi H. The relationship between salivary biomarkers and State-Trait Anxiety Inventory score under mental arithmetic stress: A pilot study. Anesthesia & Analgesia. 2005;101(6):1873-1876.

10. Rogers P, Smith J, Heatherley S, Pleydell-Pearce C. Time for tea: mood, blood pressure and cognitive performance effects of caffeine and theanine administered alone and together. Psychopharmacology. 2008;195:569-577.

11. Haskell C., Kennedy D., Milne A., Wesnes K., Scholey A., The effects of L-theanine, caffeine and their combination on cognition and mood. Biological Psychology. 2008;77(2):113-122.

12. Foxe J., Morie K., Laud P., Rowson M., De Bruin E., Kelly S. Assessing the effects of caffeine and theanine on the maintenance of vigilance during a sustained attention task. Neuropharmacology. 2012;62(7):2320-2327.

13. Borzelleca J., Peters D., Hall W. A 13-week dietary toxicity and toxicokinetic study with l-theanine in rats. Food and Chemical Toxicology. 2006;44(7):1158-166.

14. Longo L, Johnson B. Addiction part I. benzodiazepines – side effects, abuse risk, and alternatives. American Family Physician 2000;61(7):2121-2128.

15. Alexander J., Hillier A., Smith R., Tivarus M., Beversdorf D. Beta-adrenergic modulation of cognitive flexibility during stress. Journal of Cognitive Neuroscientists. 2007;19(3):468-478.

16. Corrigan, P. How stigma interferes with mental health care. American Psychologist. 2004;59(7): 614-625.

17. Keenan E, Finnie M, Jones P, Rogers P, Priestley C. How much theanine in a cup of tea? Effects of tea type and method of preparation. Food Chemistry. 2011;125:588-594.


Henry Gong

Biology, Public Policy

Henry Gong

Biology, Public Policy