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What is L-theanine?

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What is L-theanine?

L-theanine is an amino acid compound that is usually produced by extracting green tea (Camellia sinensis) leaves. L-theanine has also been found in brown dates (Imleria Badia). As a supplement, theanine is generally considered relaxing and has been used for a long time, e.g. as an ingredient in nutritional supplements. Its use is especially popular in the morning with coffee and in the evening before going to bed. Theanine is especially used to increase peace of mind and facilitate falling asleep. Read more about the benefits and potential harm of using L-theanine.


The effect of L-theanine


The effect of L-theanine is long-lasting. It is used to reduce stress and mental fatigue. Taken in the evening, it is said to improve and deepen the quality of sleep. In the morning with coffee, L-theanine calms and balances the effect of caffeine.


Accelerates falling asleep


According to studies also published in the journal Nutrients, L-theanine can be helpful for cognitive functions and the treatment of insomnia, as it seems to speed up falling asleep and reduce sleep disturbances. In the study, subjects were given 200 mg of L-theanine once a day for a total of four weeks. Results were compared with placebo and L-theanine and theanine appeared to have several positive effects. Research suggests that L-theanine may be a potential way to promote mental health in people with cognitive impairment and stress-related challenges. (1)

Increases the amount of alpha waves in the brain


The state of alertness and activation levels of the brain can be measured using the EEG electroencephalogram. During stress, with the help of EEG, the brain often seems to have a lot of beta waves. In a relaxed state, the number of alpha waves increases and beta waves decrease. Taking L-theanine has been shown in studies to increase alpha waves throughout the brain, which in turn produces a relaxing effect.


Reduces stress

L-theanine has been found in studies to increase the activity of the parasympathetic nervous system, which manifests as relaxation of the body. For this reason, some also use L-theanine to reduce tension and anxiety.


Increases concentration

Theanine affects the alpha waves of the brain, creating a state of relaxation, which in turn may help to concentrate better. Also when consumed with coffee or caffeine, L-theanine can increase cognitive performance and thus improve concentration.


Coffee, coffee beans and a press pan.

L-theanine can reduce the side effects of caffeine and improve sleep quality.


Balances the effect of caffeine

L-theanine equalizes the caffeine increase from coffee and increases cognitive performance when consumed at the same time. Theanine is especially suitable for people who are sensitive to caffeine. The caffeine in coffee begins to affect approx. in half an hour and it activates the nervous system and affects energy levels in general. The caffeine-balancing effects of theanine begin within an hour of its consumption at the latest.

In experiments, L-theanine has been found to reduce the harmful side effects of caffeine and improve the quality of sleep, when coffee has been drunk on the same day (2).


Use of L-theanine


L-theanine is usually taken once or twice a day. Usually with morning coffee or in the evening before going to bed. Theanine does not have an official daily recommended dosage, and the most often used amount is approx. 200-400 milligrams 1-2 times a day to achieve the mentioned benefits. One cup of tea contains on average about 25-60 mg of L-theanine.


L-theanine side effects


As with all other supplements, it is good to be aware of the side effects of L-theanine. Adverse effects are of particular interest to people when supplements are used together with other substances such as alcohol, coffee or medicines.

The average daily dosage of theanine is 250 to 400 mg. It is difficult to overdose on L-theanine. In some cases, doses higher than 400 milligrams may cause discomfort. Reported side effects include nausea, headache and fatigue. The use of theanine is not recommended if you tend to walk in your dreams, have nightmares or excessively intense dreams.

Green tea that contains natural L-theanine.

Natural L-theanine is produced by extracting the leaves of the green tea bush (Camellia sinensis).


Synthetic or natural


Like many other supplements, they can be made either synthetically or naturally. Of the two, natural L-theanine as an alternative is very likely a better and more researched option than synthetic chemicals. When buying L-theanine, it’s worth getting a little familiar with the background of the product and the company that sells it. Nowadays, all kinds of products are sold online as the best option on the market, although the reality may be very far from top quality. According to some studies, low-quality nutritional supplements may even do more harm than good. L-theanine, naturally made from green tea leaves, is the best option that Hamppumaa also wants to offer.

Experiences with L-theanine


On the discussion forum, you can read different experiences with L-theanine and according to many, it has been especially helpful for stress, sleep disorders and treating insomnia. In addition to capsules, adding L-theanine as a powder to the desired drink, such as water or juice, is an easy way to enjoy L-theanine based on experience. Taking L-theanine together with coffee balances the caffeine spike. Although Theanine is suitable together with coffee, it is good to remember that the possible withdrawal symptoms of coffee may feel normal despite theanine.




L-theanine may also have some interactions with other substances when used at the same time. Examples of this are alcohol and some medicines.

Consuming alcohol and theanine at the same time is not recommended because it can cause dizziness, slowing of motor reflexes and in some cases nausea.

Andrew Huberman, a famous American neuroscientist and assistant professor at Stanford University School of Medicine, recommends taking natural L-theanine together with magnesium bisglycinate or magnesium l-threonate 30-60 minutes before going to bed to treat insomnia (3).

Using L-theanine together with coffee is a popular way to balance the effects of caffeine. Several studies suggest that caffeine and L-theanine together can improve performance in cognitively difficult tasks (4).

These results echo previous evidence suggesting that L-theanine and caffeine together are beneficial for improving performance in cognitively demanding tasks.


L-theanine and drug interactions


Antihypertensive drugs and L-theanine together may lower blood pressure. Blood pressure should be monitored when medicines and theanine are used at the same time.

Also, some sedative drugs that affect the central nervous system may work together with L-theanine, increasing drowsiness and slowing of breathing. Although studies have not yet been able to confirm this repeatedly, the use of theanine should be monitored when taken together with sedatives.




L-theanine is a commonly used amino acid that, according to studies, affects e.g. relaxes the body and speeds up falling asleep. Theanine is obtained from the leaves of the tea bush (Camellia sinensis) and can increase immunity, reduce stress, increase concentration and the amount of alpha waves in the brain.

The usual daily dosage of theanine is 200-400 milligrams. L-theanine and some medications can have harmful interactions when taken at the same time. If alternatives are available, we always recommend choosing a natural alternative instead of synthetic L-theanine.



  1. Hide S. et al. 2019. Nutrients. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial . Referred on 14/12/2022.
  2. Sovijärvi O., Arina, T. Halmetoja J. 2017. The Biohacker’s Handbook. Renew yourself and release your inner potential. Biohacker’s handbook books.
  3. Huberman A. 2021. Toolkit for sleep . Referred on 14/12/2022
  4. Owen G. et al. 2008. Nutr Neurosci. The combined effects of L-theanine and caffeine on cognitive performance and mood . Referred on 14/12/2022

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