For university students, juggling assignments, quizzes, and exams can feel like a never-ending battle. With the pressure to absorb massive amounts of material in limited time, staying alert and focused is crucial. Enter caffeine—the trusty sidekick of many students during late-night study sessions. From coffee to energy drinks, caffeine is often the go-to solution for boosting energy and keeping the mind sharp. But is caffeine really the magic bullet for improved focus, or is it just a temporary fix that comes with its own set of problems?

Let’s dive into the science behind caffeine and explore how different sources—coffee and green tea—affect students’ mental performance and wellbeing.

Coffee: The Student’s Classic Choice

Coffee is by far the most popular caffeine source for students. A single 250-ml cup of coffee typically contains between 60-90 mg of caffeine, making it a powerful stimulant. But while coffee may provide an instant energy boost, it can also lead to a variety of side effects. Among the most common are restlessness, anxiety, and even insomnia—issues that are especially concerning for sleep-deprived students. After all, many students are already struggling to get enough sleep due to the demands of their coursework.

In fact, sleep deprivation is a significant challenge for university students, and it can seriously affect their academic performance. Studies show that a lack of sleep weakens your mental functions such as memory, attention, and problem-solving abilities [1]. And for students with ADHD, the problem is even worse. Research indicates that people with ADHD are more likely to experience sleep-related problems, and sleep deprivation can exacerbate their symptoms [2]. So, while coffee might help students stay awake, it could actually worsen their focus and performance in the long run.

The Green Tea Alternative

Green tea, on the other hand, offers a gentler alternative. While it contains less caffeine than coffee—around 30-50 mg per 250-ml cup—it has an additional ingredient that sets it apart: L-theanine. What is L-theanine? It is a natural compound found in tea leaves, especially green tea, and it’s known for its calming effects on the brain because it promotes relaxation and reduces stress [3]. In fact, research suggests that L-theanine can help students stay calm and focused, without the jitteriness or anxiety associated with coffee [4]. It’s no wonder that many people consider green tea to be the perfect study drink.

Unlike coffee, which can lead to a crash after the initial boost, green tea provides a more balanced experience. L-theanine works synergistically with caffeine, promoting alertness while counteracting the overstimulation that often comes with high doses of caffeine. As a result, green tea may help students stay focused for longer periods without the negative side effects of coffee.

The Science Behind Green Tea and Coffee

So, how exactly do green tea and coffee affect our brains? Both beverages work by blocking adenosine, a neurotransmitter responsible for making us feel tired. When adenosine is blocked, the brain becomes more alert and focused. However, while coffee works as a powerful stimulant, it can also cause an increase in stress hormones, leading to feelings of anxiety and nervousness. This is where green tea has an advantage.

In addition to caffeine, green tea contains L-theanine, which has calming effects. L-theanine reduces the stress and arousal caused by caffeine, promoting a more relaxed state while still maintaining focus. In other words, green tea offers a smoother, more balanced cognitive boost, while coffee can be more intense and potentially harmful to students already struggling with sleep deprivation.

Green Tea’s Impact on Anxiety and Cognitive Function

A study that compared L-theanine with a placebo (a harmless substance that looks like a real treatment but has no effect) [5] found that L-theanine helped improve brain functions, especially in speaking clearly and making decisions. [6]. Participants who consumed L-theanine showed greater verbal fluency and fewer stress-related symptoms compared to those who took a placebo. These findings suggest that L-theanine not only helps improve cognitive performance but also reduces anxiety, making it an ideal choice for students who need to study without becoming overwhelmed.

Moreover, a review of 49 studies on caffeine and L-theanine found that while caffeine enhances alertness and stamina for long-duration tasks, L-theanine helps promote relaxation and calmness [7]. When consumed together, these two compounds work in harmony to improve focus and reduce anxiety, making green tea an excellent option for students looking for a cognitive boost without the crash or stress of coffee.

Green Tea’s Benefits for Memory and Attention

Another review, which looked at 21 studies, found that green tea can help reduce anxiety while supporting memory and attention. Interestingly, the researchers discovered that the combination of caffeine and L-theanine had a greater positive impact on cognitive function than either compound alone [8]. This suggests that green tea may offer a more well-rounded cognitive boost, improving attention and working memory while keeping anxiety in check.

In contrast, coffee’s effects on memory and attention are often more short-term. While caffeine can enhance focus in the moment, it may not be as effective at supporting long-term cognitive functions such as memory recall and learning.

The Gap in Research: Coffee vs. Green Tea

While there is plenty of research on the individual effects of coffee and green tea, there is a significant gap in studies comparing the two, especially in terms of how they impact learning, memory, and mental health in young adults—particularly those with ADHD. This gap is what our research aims to address. Specifically, we are interested in exploring how coffee and green tea affect the ability of university students to recall information, focus, and learn—especially among those with ADHD.

Based on existing research, we hypothesize that green tea will be more effective at enhancing memory recall and cognitive function in young adults than coffee. We also predict that green tea may be especially beneficial for students with ADHD, as it offers a more balanced, less jittery source of stimulation. Given its combination of caffeine and L-theanine, green tea may provide the perfect balance of focus and relaxation—helping students stay alert and engaged without sacrificing their mental clarity or sleep quality.

Conclusion: Coffee vs. Green Tea—Which is Better for Studying?

So, when it comes to choosing between coffee and green tea, it ultimately comes down to personal preference and individual needs. If you need a quick energy boost, coffee may be the way to go. However, if you want a more balanced and sustainable way to stay focused, green tea may be the better option. With its combination of caffeine and L-theanine, green tea offers a gentler, more effective way to improve cognitive performance, reduce anxiety, and maintain mental clarity—especially for students juggling the stresses of university life.

Ultimately, both coffee and green tea have their place in the student’s toolkit, but it’s important to consider how each affects your body and mind. And no matter what you choose, remember: good sleep, healthy habits, and effective study techniques are the real keys to academic success.

Enjoyed the read? Go on and buy me a chamomile 😋

References

1. Hershner, S., & Chervin, R. (2014). Causes and consequences of sleepiness among college students. Nature and Science of Sleep, 73. https://doi.org/10.2147/nss.s62907
2. Surman, C. B. H., & Walsh, D. M. (2021). Managing Sleep in Adults with ADHD: From Science to Pragmatic Approaches. Brain Sciences, 11(10), 1361. https://doi.org/10.3390/brainsci11101361
3. Clinic, C. (2025b, March 3). Here’s what you need to know about L-Theanine. Cleveland Clinic. https://health.clevelandclinic.org/l-theanine
4. Kakuda, T. (2011). Neuroprotective effects of theanine and its preventive effects on cognitive dysfunction. Pharmacological Research, 64(2), 162–168. https://doi.org/10.1016/j.phrs.2011.03.010
5. Anderson, L. A. (2024, October 1). What is the Placebo Effect? Drugs.com. https://www.drugs.com/article/placebo-effect.html
6. Hidese, S., Ogawa, S., Ota, M., Ishida, I., Yasukawa, Z., Ozeki, M., & Kunugi, H. (2019b). Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in healthy adults: a randomized controlled trial. Nutrients, 11(10), 2362. https://doi.org/10.3390/nu11102362
7. Dietz, C., & Dekker, M. (2017). Effect of green tea phytochemicals on mood and cognition. Current Pharmaceutical Design, 23(19), 2876–2905. https://doi.org/10.2174/1381612823666170105151800
8. Mancini, E., Beglinger, C., Drewe, J., Zanchi, D., Lang, U. E., & Borgwardt, S. (2017). Green tea effects on cognition, mood and human brain function: A systematic review. Phytomedicine, 34, 26–37. https://doi.org/10.1016/j.phymed.2017.07.008