L-Theanine Benefits: Supporting Focus, Sleep, and Brain Health

By Ken Swartz, MS If you make a cup of green tea to feel a little calmer and clearer, you already know something about the benefits of L-theanine. This gentle amino acid is one of the main reasons tea has a reputation for promoting relaxation and smooth, steady focus, which feels very different from the quick jolt many people get from coffee. In this article, we explore the well-known benefits of L-theanine and what current research suggests. You’ll learn how this unique amino acid may support calm focus, sleep quality, mood, and long-term brain health, as well as how its mechanisms compare to those of Carbon 60 (C60). The goal is to help you understand how L-theanine works on the mind, how C60 works on the cellular level, and how each may fit into a thoughtful, science-backed wellness routine.

L-Theanine Basics: What It Is and How It Functions

L-theanine is a natural water-soluble amino acid found mostly in tea leaves.¹ It gives green tea much of its “smooth,” relaxed feel. L-theanine also lends to the distinguishable tea flavor that so many of us enjoy. Unlike protein-building amino acids, L-theanine mainly affects the brain and nervous system. When you take L-theanine, it is absorbed from your gut into your bloodstream. From there, it can cross into your brain. Researchers describe it as neuroactive because it interacts with brain cells and signaling chemicals. A large review in Frontiers in Nutrition notes that L-theanine may have calming, antioxidant, and brain-protective effects in animals and humans.¹ Though the chemistry behind it can be quite complex, the main takeaways in familiar terms include:¹

• It may raise levels of calming brain messengers or neurotransmitters, like gamma-aminobutyric acid (GABA).
• It may also support the feel-good messengers such as dopamine and serotonin.
• It seems to increase alpha brain waves, which are linked with relaxed alertness, similar to gentle meditation or just feeling relaxed.

Beyond Green Tea — Dietary Sources of L-Theanine

L-theanine is found mostly in: ^2,3

• Green tea, white tea, matcha, oolong, black tea
• Some mushrooms like bay boletes

• A typical cup of brewed green tea gives roughly 5 to 20 mg of L-theanine, which may contribute to that soft, gentle calming effect in some people.
• Keep in mind that the L-theanine content can vary in teas secondary to tea processing and preparation time.³

How L-Theanine Supports Brain Health

Once L-theanine crosses the blood-brain barrier, it interacts with several brain systems. Research suggests it can:

• Increase GABA, a calming chemical that helps quiet nervous activity.
• Support regulation of dopamine and serotonin, which influence motivation, pleasure, and mood.⁴
• Raise alpha brain waves, which are linked with relaxed yet alert states, not heavy sedation.¹

A 2022 review article on L-theanine in tea highlights these brain wave and neurotransmitter changes as key reasons for its stress and mood effects.¹ In the day-to-day, people sometimes explain that it is a feeling of calm, but totally aware or quietly focused after taking L-theanine.

How L-Theanine Affects Dopamine

L-theanine can increase dopamine levels in the brain, according to some animal studies. It achieves this by promoting the release of dopamine in the striatum and may also have neuroprotective effects, particularly in models of Parkinson’s disease.

• Increases dopamine release: Studies in rats have shown that L-theanine can directly cause a significant increase in dopamine release in the striatum.¹¹
• Structural similarity: L-theanine is structurally similar to glutamate, which suggests it may influence the glutamate receptor system, leading to increased dopamine release, as reported in one ScienceDirect article.¹¹
• Neuroprotective role: In a model of Parkinson’s disease, L-theanine was found to improve symptoms by replenishing dopamine levels and protecting dopaminergic neurons.¹¹

Typical L-Theanine Dosage and Safety

Most human studies on l-theanine benefits use daily doses in the 100 to 200 mg range. Some use more, especially in divided doses during the day, but higher amounts are still being studied.⁴ This is not considered medical advice, nor are these recommendations, but results of studies. Common supplement doses are much higher, usually 100 to 200 mg per serving. You will see it in:

• Brewed green or matcha tea
• Capsules or tablets
• Powders you can add to drinks
• Blends that combine L-theanine with caffeine

L-theanine is generally recognized as safe for most healthy adults when used as directed.² Talk with a healthcare provider before use if you are pregnant, nursing, on medications, or have health conditions.

Potential Benefits of L-Theanine

L-theanine has been studied for several key areas that matter in daily life: stress, sleep, focus, and mood. A 2024 systematic review in BMC Psychiatry found support for benefits in stress, anxiety, sleep, and some aspects of cognition, though more high-quality trials are needed.⁵

Supports Stress Management and Focus

One of the most popular l-theanine benefits is stress relief without feeling tired or sluggish. In a 2019 trial in stressed adults, daily L-theanine supplementation reduced stress-related symptoms and lowered stress hormone levels, including cortisol.⁶ Participants reported feeling less anxious and more focused.⁶ Real-life situations where this may help include:

• Public speaking or giving a presentation
• Busy workdays with tight deadlines
• Social events that trigger worry or tension
• Travel days, airports, and long drives

L-theanine is not a replacement for therapy, medication, or crisis care. Anyone with strong or ongoing anxiety or depression should work with a qualified mental health professional.

Sleep Support

As you may know, L-theanine helps to quiet the mind, which can make it easier to fall asleep and stay asleep. A 2025 paper on L-theanine and sleep found that doses around 200 mg before bed improved sleep quality and relaxation, especially in people with mild stress or trouble relaxing.^4,5,6 Simple habits that work well with L-theanine for sleep that you may want to consider include:

• Turning the lights down about 1 hour before bed
• Putting the phones, tablets, and laptops to rest too
• Keep a regular bedtime and wake time, which also supports a healthy circadian rhythm
• Try establishing a simple wind-down routine, like light stretching, reading, or meditation

Focus, Clarity, and Caffeine

Another well-known benefit of L-theanine is better focus, especially when taken with caffeine. In several studies, a combo of about 100 mg caffeine plus 200 mg L-theanine improved attention, reaction time, and accuracy compared with caffeine alone.^{7 ,9} The L-theanine appears to support calmness, while keeping individuals alert to focus on their tasks or projects. A classic study in Nutritional Neuroscience found that this mix improved both speed and accuracy on attention tasks and reduced mental fatigue.^7,9

Brain Health and Mood Support

Researchers are also looking at L-theanine for long-term brain health and mood support. Early findings suggest it may:

• Help protect brain cells from stress-related damage
• Support growth factors involved in brain plasticity and memory
• Promote a more stable, positive mood through balanced brain chemicals^4,7

For example, a study in middle-aged and older adults found that single doses of L-theanine improved attention and some measures of cognitive performance.¹⁰ A technical report from the Alzheimer’s Drug Discovery Foundation also highlights possible neuroprotective effects, though evidence is still mixed and developing.¹⁰ L-theanine should be viewed as one piece of a brain-healthy lifestyle, along with sleep, movement, social connection, and a nutrient-rich diet.

L-Theanine, C60, and How They Work Together for Brain and Body Support

L-theanine is not the only supplement people look at for brain and cell support. Another is C60, short for carbon 60. C60 is a special form of carbon that looks like a tiny soccer ball under a microscope. Scientists first studied it in chemistry labs, then started testing it in animals and cells. Research suggests C60 can act as a strong antioxidant and promotes a balanced immune response.⁸  Key proposed benefits in early research:

• Cell protection from oxidative stress*
• Energy support, by helping protect mitochondria in cells*
• May support anti-aging effects*

L-Theanine vs Carbon 60 (C60) Buckminsterfullerene

Here is a simple comparison of L-theanine and C60.

Feature	L-Theanine	Carbon 60 (C60) Buckminsterfullerene
Main Source	Amino acid from tea leaves	Pure carbon molecule from lab synthesis
Main Action	Calms brain chemicals and supports alpha waves	Acts as a strong antioxidant and membrane support
Primary Researched Benefits	Stress, sleep, focus, mood	Cellular, antioxidant, energy, recovery, and longevity support
Human Research Strength	Moderate to strong for stress, sleep, focus4	Early, mostly animal and in-vitro studies with emerging human interest7
Common Forms	Tea, capsules, powders, or paired with caffeine/nootropics	Oil-based solutions (olive, avocado, MCT), capsules, and topical preparations
Typical Use Cases	Calm focus, better sleep, daily stress	Long-term cell and brain support, experimental longevity protocols
Speed of Effect	Often noticeable within 30–60 minutes	Effects are typically gradual, supports long-term cellular balance rather than immediate sensations
Role in Wellness Routine	“Acute support” for stressful moments, busy workdays, or bedtime routines	“Foundational support” aimed at deeper cellular defense and helping manage oxidative stress over time*

L-theanine and C60 play very different roles in a wellness routine—one offers calm clarity in the moment, while the other provides deeper, long-term cellular support. L-theanine helps settle the mind, promote relaxation, and support focused attention, whereas C60 works at the membrane level, helping the body manage oxidative stress over time.* When used together, they create a balanced approach: immediate mental ease paired with ongoing antioxidant defense. Many individuals appreciate combining both to support a steadier, more resilient sense of well-being.*

Key Takeaways

• L-theanine is a naturally occurring amino acid from tea that supports calm focus, relaxation, and improved sleep quality.
• It works by influencing brain messengers like GABA, dopamine, and serotonin, and by increasing alpha brain waves linked with relaxed alertness.
• C60 supports the body differently by helping protect cells from oxidative stress and promoting a balanced cellular environment over time.*
• L theanine offers more immediate mental support, while C60 provides deeper and longer lasting cellular support.*
• Using both may offer complementary benefits, with L-theanine supporting clarity in the moment and C60 helping maintain long-term cellular resilience.*
• Always speak with your healthcare provider (HCP) if you have medical conditions, take medications, or plan to stack several supplements.

Summary

Pairing C60 with L-theanine may be beneficial if your goal is steadier energy and clearer focus, but it helps to keep the evidence straight. L-theanine has solid human research showing it can promote calm and support attention, often without making you drowsy, which is why people like it for daytime stress and that ‘wired’ feeling. If your objective is to bolster your cellular health and mitochondrial function, selecting C60, known for its strong antioxidant properties and its association with mitochondrial performance, may be a beneficial addition to your existing nutritional plan. While there is considerable potential in utilizing supplements such as C60 and L-theanine, it is wise to consult with your healthcare provider regarding these or any other supplements before commencing their use. Regarding C60 Power, numerous individuals have reported improvements in energy levels and mental clarity. Disclaimer *These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, mitigate, or prevent any disease. Individual results may vary.

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References

1. Li, Meng-Yao, et al. “L-Theanine: A Unique Functional Amino Acid in Tea with Multiple Health Benefits.” Frontiers in Nutrition, vol. 9, 2022, article 853846, https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.853846/full.
2. “Here’s What You Need to Know About L-Theanine.” Cleveland Clinic Health Essentials, 19 July 2023, https://health.clevelandclinic.org/l-theanine.
3. Anas, Brittany Leigh. “Tea and Foods Rich in Theanine.” EverydayHealth.com, 2025, www.everydayhealth.com/food-ingredients/foods-rich-in-theanine/.
4. Moshfeghinia, Razieh, et al. “The Effects of L-Theanine Supplementation on the Outcomes of Mental Health.” BMC Psychiatry, vol. 24, 2024, article 62, https://bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-024-06285-y.
5. Cotter, Joseph, et al. “Examining the Effect of L-Theanine on Sleep.” Nutritional Neuroscience, 2025, https://www.tandfonline.com/doi/full/10.1080/1028415X.2025.2556925.
6. Hidese, Shinsuke, et al. “Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults.” Nutrients, vol. 11, no. 10, 2019, article 2362, https://pmc.ncbi.nlm.nih.gov/articles/PMC6836118/.
7. “L-Theanine Cognitive Vitality for Researchers.” Alzheimer’s Drug Discovery Foundation, 2020, https://www.alzdiscovery.org/uploads/cognitive_vitality_media/L-Theanine-Cognitive-Vitality-For-Researchers.pdf.
8. “Carbon 60 Benefits | C60 Supplement Benefits | C60 Purple Power.” C60 Power, 22 Apr. 2025, shopc60.com/pages/c60-health-benefits/. https://shopc60.com/pages/c60-health-benefits/
9. ‌Owen, Gail N., et al. “The Combined Effects of L-Theanine and Caffeine on Cognitive Performance and Mood.” Nutritional Neuroscience, vol. 11, no. 4, 2008, pp. 193–198, https://pubmed.ncbi.nlm.nih.gov/18681988/.
10. Baba, Yasuhisa, et al. “Effects of L-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study.” Journal of Medicinal Food, vol. 24, no. 4, 2021, pp. 333–341, https://pmc.ncbi.nlm.nih.gov/articles/PMC8080935/.
11. Wang, Liwen, et al. “How Does the Tea L-Theanine Buffer Stress and Anxiety.” Food Science and Human Wellness, vol. 11, no. 3, 1 May 2022, pp. 467–475, https://www.sciencedirect.com/science/article/pii/S2213453021001324.