How Does L-Theanine Promote Sleep?

For centuries, L-theanine has been consumed as an addition to tea. But, according to research, L-theanine can actually make you sleep better.

L-theanine promotes sleep by soothing your mind, and thus, your body. But, what is L-theanine and how does it make you sleep better? In this article, we will answer these questions!

L-Theanine & Sleep


In simple words, L-theanine is a compound, or amino acid, that can be discovered in the leaves of certain plants. The tea plant, or Camellia sinensis, is the most common example. If you’ve ever consumed tea, you’d be familiar with the stress-free sentiment you feel afterwards; that’s the L-theanine.

It is acclaimed by many people as a supplement to sleep better without any sedative influence.
L-theanine only takes 30 minutes to sooth the mind and make the consumer feel more aware. L-theanine is a renowned supplement combined with tea and has been acclaimed by many researchers as a method to decrease apprehension and tension, and reduce blood pressure. And, it has also been acclaimed as an organic chemical to avoid insomnia and promote sleep.

L-theanine is often added to coffee, as it enhances the influence of caffeine on the mind without the uneasiness and restlessness that is causes. The proportion between caffeine and L-theanine is recommended to be 2:1. Even though L-theanine is present in all forms of tea, matcha green tea has the most amount of it.

L-Theanine & Sleep


There are two foremost classifications of neurons; excitatory – the ones that prevent sleep and secrete the neurotransmitter, glutamate; and inhibitory – the ones that stimulate sleep and secrete the neurotransmitter, GBA. L-theanine performs its part by improving the function of inhibitory neurons.

As a result, the neurotransmitter, GBA, is secreted, which in turn makes sleep better. And, L-theanine also decreases the function of excitatory neurons, which prevents sleep. The outcome to this is more sleep and a serene state of mind.


L-theanine is acclaimed as a cure for tension and promoting calmness and concentration. As a result, L-theanine makes you sleep better. And, L-theanine also improves sleep by prolonging it and making you feel more revitalised.

Since L-theanine does not contain any sedative elements, it is not addictive and does not make you feel lethargic. And, it is also free of all the detrimental consequences that sedative elements have. According to a research conducted on the substance, a review states that L-theanine is a “safe natural aid for the improvement in sleep quality in all age groups”.

L-Theanine & Sleep


Over the years, there have been many studies conducted on both animals and humans to show the L-theanine on the mind and body. In the end, the results almost always proved how operative the compound is. These studies also prove that L-theanine does what it’s marketed as without causing any destructive results.


From the research conducted on rats, the results always showed an improvement in caffeine-caused sleep.


L-theanine research has been conducted on humans, however, the complication is that these studies were based in Japan and never translated to English. But, the influence of L-theanine as a stress-reducing and soothing supplement have been documented across the world, so there’s an abundance of indirect indication that L-theanine promotes sleep.

As per a randomized, double-blind, crossover review conducted on 20 men, L-theanine was found to make sleep better. It also improved the dreams, disposition, self-assurance, and the feeling of being revitalized when waking up. The review assessed them by giving them either a placebo or L-theanine medications an hour before going to sleep and were presented with a questionnaire afterwards. A similar review was then conducted on 20 older women and the results remained the same. The conclusion of this reviews was that “L-theanine can be considered an excellent aid for improving the sleep state”.

Another randomized, double-blind review conducted on 93 boys between the age of 8 and 12 with ADHD showed the use of L-theanine as a support for sleep. The boys were either given a placebo or L-theanine medications as breakfast and after school on a routine basis, for 6 weeks. L-theanine was found to increase sleep more and improve it as well. The conclusion of this reviews was that “400 mg daily of L-theanine is safe and effective in improving some aspects of sleep quality in boys diagnosed with ADHD”.

Another double-blind review was conducted on 12 healthy individuals. The individuals were given either a placebo or L-theanine medications while performing a tense mathematics process. From the results, individuals that took the L-theanine medications showed a decrease in heart-rate and salivary immunoglobin, both of which are indications of stress. The conclusion of this reviews was that “oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation”.

According to a review conducted on 20 healthy men between the age of 18 and 30, L-theanine was found to promote a stress-free and focused state of mind. The men were given either a placebo or L-theanine medications and had their brain performance evaluated afterwards. The conclusion of this reviews was that “L-theanine containing tablets promote the release of alpha waves related to mental relaxation and concentration in young adult males”.


For improving sleep, researchers recommend a dose of 200-400 mg L-theanine. Often than not, reviews use a patented form of untainted L-theanine known as Sun-theanine.

In stores, L-theanine is sold in 100-200 mg capsules. Tea consumers intake between 15-375 mg of L-theanine on a routine basis, 1-3 cups of tea.

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