Sebastian Freidank - 18. February 23

L-Theanine Effects - Concentration, Sleep, Depression & Caffeine


The L-Theanine effect is extremely exciting in many ways! Especially in combination with caffeine, L-theanine has a terrific effect! But L-theanine can also have a positive effect on sleep and depression.

In this article, we would like to focus on the effects of L-Theanine so that in the end you understand exactly what advantages this exciting amino acid has and how you can use it for yourself.


  1. What is L-Theanine?
  2. Where is theanine found?
  3. L-Theanine Effect
    1. General usage of L-Theanine
    2. Concentration – L-Theanine Effect
    3. L-theanine effect on sleep
    4. L-theanine effects on stress
    5. immune system
    6. L-theanine effect in depression
    7. blood pressure
  4. Effect L-theanine and caffeine
  5. L-theanine dosage
  6. Side Effects of L-Theanine
  7. Conclusion

1. What is L-Theanine?

L-Theanine is a non-proteinogenic amino acid. It is therefore not incorporated into the body as a protein. The amino acid acts in the brain and is therefore one of the few that can cross the brain-blood barrier. The effects of L-theanine are described as relaxing, reducing stress and anxiety, and improving sleep. More on the effect later.

2. Where is theanine found?

Rarer than gold, one could almost say, because L-theanine is only found in two plants and one mushroom. At least no other source has been found so far.

  • Guayusa
  • Camellia Sinensis
  • chestnut boletus

For a pure L-theanine powder, you have to carry out an extraction, as with caffeine .

Where is L-Theanine found?

3. L-Theanine Effect

3.1. General usage of L-Theanine

Because L-Theanine has a relaxing effect, many people use it to reduce stress or to reduce anxiety and depression. L-theanine is often taken in dissolved form as a tea or as an extract.

It is also said to increase mental performance and alertness and lead to increased focus. In addition, it should have a blood pressure-regulating effect and improve the quality of sleep.

Let's take a closer look at the mentioned effects of theanine.

3.2. Concentration – L-Theanine Effect

Taking L-theanine is said to improve concentration and learning ability. This can be beneficial before an important test or during demanding mental work. In a study on the effect of L-theanine on cognitive abilities, it was found after just one intake that the test persons cut off faster and with fewer errors in reaction tests. The study came  after 12 weeks to the conclusion that attention, memory capacity of the brain and executive processes are positively influenced.

3.3. L-theanine effect on sleep?

One study looked at the effect on our sleep. A 2011 study shows that L-theanine induces deeper and more relaxed sleep. After just 6 weeks of taking 100 mg of L-theanine twice a day, the participants' sleep patterns improved.

Another study showed that 200 mg to 400 mg significantly improved sleep in both humans and animals.

Further investigations showed a lower heart rate in the resting mode of the subjects and a better sleep quality of ADHD boys.

3.4. L-theanine effects on stress

Research has shown that L-Theanine has a calming effect on the mind without making you drowsy. In addition, the amino acid is said to help reduce stress and anxiety in stressful situations.

L-theanine effects overview

3.5. immune system

A study on L-theanine in beverages was also able to demonstrate a reduction in respiratory diseases and intestinal infections .

3.6. L-theanine effect in depression?

Similar to the studies on anxiety and stress, studies in patients with chronic depression come to the conclusion that L-theanine has a soothing effect.

3.7. blood pressure

In a study conducted in 2012 on the effect of L-theanine on people who tended to have high blood pressure in stressful situations, it was observed that taking around 200 mg of L-theanine beforehand lowered the blood pressure of the subjects.

Five other studies that reviewed the use of L-theanine at regular intervals also led to these blood pressure-lowering results.

In two Japanese studies, a remarkable L-theanine effect was found. L-Theanine has been shown to lower blood pressure only when there is a problem, not when there is no stress causing a rise. L-theanine can therefore be described as blood pressure regulating rather than lowering.

4. Effect of L-theanine and caffeine

The combination of L-theanine and caffeine has often been examined in studies and showed better attention in the test subjects and ability to solve the tasks set. Participants also felt more relaxed and alert.

In general, it seems that attention, mood, memory and reaction are significantly improved .

Effect L-theanine and caffeine

5. L-Theanine Dosage

There is no official dosage recommendation for L-theanine, but studies can quickly conclude that a daily dose of 200 mg to 400 mg has an efficient and positive effect. This dose can be taken for 4 to 6 weeks or longer.

Of course, if you are inclined to start a self-experiment, we advise you to inform your doctor and ask for advice and get more information.

6. L-Theanine Side Effects

So far, no L-theanine side effects are known. An intake as a supplement of 900 mg daily was tested in studies over 8 weeks. Of course, this is not a medical recommendation. Contact your doctor and get more information.

Guayusa tea contains both L-theanine and caffeine. You can find information about the benefits and disadvantages of caffeine in our extra articles. A complete overview of the active ingredients in Guayusa can be found here .

7. Conclusion

L-Theanine is an ingenious active ingredient with a terrific effect that can help against stress, anxiety and depression. But not only that, L-theanine improves sleep and cognitive abilities - according to the study.

The effect is therefore not only for professional biohackers , but also for students, the self-employed and everyone who is often exposed to stressful situations and mental challenges.

In combination with caffeine and other active ingredients such as theobromine and theophylline, L-theanine can develop a synergistic effect.

Guayusa tea

Organic Guayusa from GUYA is original Guayusa from Ecuador. You can order our Guayusa directly from our shop and have it delivered to your home.

GUYA is Europe's first and largest Guayusa brand that offers you a large selection of Guayusa products. Our versatile Guayusa blends bring variety to your everyday life, keep you awake, focused and relaxed at the same time.

Since 2016 we have been working directly with farmers from Ecuador without intermediaries and have learned a lot about the processing of guayusa.

We look forward to your Guayusa order. 

Powder Guayusa

Buy pure guayusa tea powder. Our Guayusa powder offers you a variety of preparations without losing the organic quality.

Our PURE Guayusa Powder is original Guayusa, but particularly finely sieved to extract the powder particles . You can use the Guayusa powder in preparation of  a latte, cappuccino, espresso or for smoothies and pastries.

With the use of our Dripper , Guayusa powder can easily be used to prepare tea. The dripper's has a double-walled sieve that prevents the powder particles from getting into your tea. This way you can enjoy a delicious Guayusa tea without tea leaves in the water.


The Guayusa sets contain all our Guayusa tea flavours  as well as our tea accessories.Purchasing Guayusa in Sets is a best way to save money because  the Guayusa is in cheaper price in Sets than when sold as an individual product.

Our Guayusa comes from Ecuador and is organically grown there and traded fairly by us.

Each Guayusa set is put together differently and offers you a cheap alternative to expensive individual orders. Choose from sets with a teapot, tea glass, thermos flask, tea strainer and our 7 Guayusa varieties.


Our high-quality tea accessories made from stainless steel and special borosilicate glass have a long service life and can withstand all temperatures unconditionally! Find the right tea accessory for you in our online shop!

The glass products, as well as our stainless steel tea strainers, are suitable for any loose tea. All products can easily be cleaned in the dishwasher or under running water.

You can buy our products individually or in a combined package at a lower price.

Our tea accessories online shop also offers you a large selection of Guayusa tea which all together, as a set, make   an excellent gift.

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