L-Theanine for Better Sleep?

“L-theanine has the greatest effect on sleep quality rather than sleep length; however, does seem to aid sleep. L-theanine does so by affecting the brain’s capability of using/interacting with glutamate, a neurotransmitter that excites the brain, and downplaying the overall excitement of the brain, allowing your brain to enter a calmer state of being." At the time of this writing, there seems to be relatively little research on the topic of l-theanine and its sleep effects. However, there is some data that has been done, especially across seas, in Japan. So, in this research review [Figure 1], I’ll break down the little literature on the topic and offer some useful take-aways on the potential sleep aid l-theanine.


1. What is L-Theanine?


L-theanine is simply an amino acid, like those that make up proteins, produced from the metabolism of two other amino acids – alanine and glutamate. It is found in higher concentrations in certain teas like green and black tea.


2. Does it improve sleep?


The information I’ll be presenting to you comes from a small research review [Figure 1] that attempted to find out, combining the data of several small studies, how l-theanine affects sleep. They found, across multiple measures like sleep quality, dream quality (fewer nightmares), as well as mood the following day, that l-theanine did provide a small benefit [Figure 2]. However, sleep length did not improve. So, l-theanine seems to improve the quality of sleep far more than it improves the actual duration of sleep. This is an important distinction, because while often people consider sleep length the best indicator, and it certainly is vital, it isn’t the only metric – sleep quality is equally important, although more abstract to measure.



3. How does L-Theanine improve sleep?


L-theanine’s mechanisms are still being investigated, but it’s believed that l-theanine’s chemical structure is similar to the excitatory neurotransmitter known as glutamate. Glutamate, when it binds the neurons (brain cells), excites, or activates – which means it reduces the ability for humans to fall asleep. L-theanine’s action may be through blocking glutamate from binding the neurons by competing for the same binding domain/receptor on the brain cells [Figure 3]. Additionally, it may promote the release of GABA, another neurotransmitter, that has a calming effect when it interacts with the neurons.

Conclusions


L-theanine has the greatest effect on sleep quality rather than sleep length; however, does seem to aid sleep. L-theanine does so by affecting the brain’s capability of using/interacting with glutamate, a neurotransmitter that excites the brain, and downplaying the overall excitement of the brain, allowing your brain to enter a calmer state of being.

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