The Health Benefits and Safety of L-Theanine and Melatonin

In this article, we will take a close look at L-Theanine and Melatonin, two compounds often used as supplements for their calming effects. We will delve into their individual health benefits, their safety when taken together, and their potential to improve sleep quality and reduce anxiety.
Natasha Puttick

Natasha Puttick

Graduate medical student at Barts and London.

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What is L-Theanine?

L-theanine is a major amino acid uniquely found in green tea and some mushrooms. It's a nonproteinogenic amino acid, meaning it doesn't contribute to the formation of proteins in the body [1, 2]. This compound is known for its potential health benefits and is often used as a supplement for its calming effects [3]. It can also be supplemented by taking pills or L-Theanine gummies

L-theanine has been reported as a relaxing agent, prompting scientific research on its pharmacology. It's suggested that L-theanine increases brain serotonin, dopamine, GABA levels, and has micromolar affinities for AMPA, Kainate, and NMDA receptors [1].

In addition to its calming effects, L-theanine has been shown to exert neuroprotective effects in animal models, possibly through its antagonistic effects on group 1 metabotrophic glutamate receptors. It's also suggested that L-theanine may improve learning and memory [1].

Furthermore, L-theanine exhibits strong antioxidant-like properties and contributes to the favorable umami taste sensation. It has been associated with improvements in brain and gastrointestinal function, cancer drug therapeutic efficacies, antihypertensive effects, and improved immune function [4].

L-theanine should not be confused L-Thyrosine

What is Melatonin?

Melatonin, also known as N-acetyl-5-methoxy tryptamine, is a hormone that is naturally produced by the human body, primarily by the pineal gland located in the brain [5, 6]. This hormone plays a crucial role in regulating the body's circadian rhythm, which is the internal clock that dictates sleep-wake cycles [5, 7].

Melatonin production increases in the evening, inducing sleepiness at night and promoting wakefulness during the day [6]. It is often referred to as the 'hormone of darkness' because its secretion is stimulated by darkness and inhibited by light [8, 9].

In addition to its role in sleep regulation, melatonin has been found to interact with more than 15 proteins, including receptors, enzymes, transporters, and other proteins, at varying concentrations [10]. It also has antioxidant properties and plays a role in the regulation of the cell cycle [6].

Melatonin is available as a dietary supplement and is often used to address sleep disorders, jet lag, and certain circadian rhythm disorders [5]. However, it's important to note that the National Institutes of Health’s National Center for Complementary and Integrative Health (NCCIH) states that there's not enough evidence to recommend melatonin as a treatment for chronic insomnia [5].

Is it safe to take Melatonin and L-theanine together?

Yes, it is generally considered safe to take L-theanine and melatonin together. Both substances are commonly used to promote relaxation and improve sleep quality.


L-theanine, an amino acid found in tea leaves, has been shown to have anxiolytic effects, promoting relaxation without causing drowsiness. It has been used to improve sleep quality, not through sedation, but through reducing anxiety [11]. In a study involving patients with schizophrenia and schizoaffective disorder, L-theanine was found to be a safe and well-tolerated medication [12].

Melatonin, on the other hand, is a hormone that regulates the sleep-wake cycle. It's often used as a sleep aid, especially for issues related to jet lag or insomnia. A study investigating the effects of melatonin and theanine (Mel/Thea) on seizures and brain tissue oxidative damage in rats found that the combination of these substances demonstrated antioxidant and anticonvulsant activities [12, 13].

However, while these substances are generally safe for most people, individual reactions can vary. It's always recommended to consult with a healthcare provider before starting any new supplement regimen, especially if you're currently taking other medications or have underlying health conditions.

What are the benefits of taking Melatonin and L-theanine together?

There may not be sufficient evidence to answer exactly as scientific studies do not specifically address the combined effects of taking L-theanine and melatonin together. However, the individual benefits of L-theanine and melatonin can be discussed.

Benefits of L-Theanine

L-Theanine, an amino acid found in tea leaves, has been associated with several health benefits. It has been shown to improve sleep quality not by sedation, but through anxiolysis, the process of reducing anxiety. A study suggests that the administration of 200 mg of L-theanine before bed may support improved sleep quality [14].

L-Theanine has also been found to assist in the reduction of stress and anxiety in people exposed to stressful conditions, with a supplementation of 200-400 mg/day suggested [15].

In terms of cognitive function, L-theanine has been found to increase focus and attention, especially when paired with caffeine [16, 3].

Benefits of Melatonin

Melatonin is widely recognized in the scientific community as a hormone that plays a key role in regulating the sleep-wake cycle. It is often used as a supplement to aid in sleep issues such as insomnia or jet lag. Aside from that it has other benefits:

In conclusion, while both L-theanine and melatonin have their individual benefits, particularly in relation to sleep and anxiety, the scientific evidence for their combined use is lacking. It is always recommended to consult with a healthcare provider before starting any new supplement regimen.

Natasha Puttick

Natasha Puttick

Natasha is a medical student at Barts and the London school of Medicine and Dentistry, with an interest in the social determinants of health. She graduated from the University of Oxford with a BA in Human Sciences and has obtained two publications. Her most recent work investigating clinical vaccine trials has been published in BMJ Public Health.