L-theanine aids in anxiety and sleep disorders

What is L-theanine, and what is it used for? L-theanine (also called theanine or sometimes r-glutamylethylamide) is an amino acid that impacts nerve impulses in the brain and the release of neurotransmitters, including GABA.

It is known as a natural anxiolytic because it can have a calming, sedative effect on the body and mind without making you feel drowsy — which is why it’s often used to reduce anxiety, hyperactivity, and sleep-related problems.

Most people don’t acquire a lot of theanine from their diets since it’s not available in many commonly eaten foods. It’s a unique amino acid because it’s not used to form proteins — unlike many other amino acids, such as l-carnitine, leucine, lysine, methionine, or tryptophan — and is not used to make enzymes.

The greatest sources of L-theanine in our diets are green, black, and white teas — but because most people don’t drink very large quantities of tea on a daily basis, L-theanine supplements can be beneficial.

As we’ll cover more below, drinking tea and taking L-theanine supplements can help reduce the effects of stress, protect the brain, support the cardiovascular system, and much more.

What Is L-theanine?

L-theanine is considered a non-dietary, nonessential amino acid because even though it has certain benefits, we don’t require it from our diets.

What does L-theanine do for you? It is used to help prevent and treat conditions, including:

  • Anxiety, depression, and other mood-related disorders
  • Insomnia and trouble sleeping
  • Cognitive loss, dementia, and Alzheimer’s disease
  • Stroke
  • High blood pressure and other cardiovascular problems

L-theanine and the amino acid glutamine are structurally similar but have different effects and benefits. Both can be supportive of overall mental health and energy levels, but theanine is more capable of acting as a natural stress reliever.

Researchers believe that umami flavor may actually affect the brain in a way that helps decrease the risk for obesity, stimulate the metabolism, alter taste perception of bitter foods, boost satiety and fullness, and hold off hunger and cravings between meals.

Because each type has unique properties, many tea varieties are included in the Ayurvedic diet, such as:

  • Jasmine green tea, which can also have sedating effects on the nervous system.
  • Moroccan mint green tea, which can help to soothe digestive issues and nausea.
  • Matcha tea contains concentrated levels of L-thiamine.

Green tea has been consumed in China and other parts of Asia for thousands of years. According to Traditional Chinese Medicine (TCM), tea is the most beneficial of all herbs and has numerous benefits, including improving alertness, supporting immunity, balancing body fluid production, quenching thirst, clearing heat and phlegm, and promoting healthy digestion and urination.

While green tea is most valuable in TCM, many other types of teas are also encouraged, including white, black, and oolong teas.


What are the benefits of L-theanine? Below are five ways it can benefit your sleep, mental health, cognition, and more.

1. Can Help Relieve Anxiety and Reduce the Effects of Stress

One of the most well-researched L-theanine benefits is its ability to promote relaxation and fight stress. It is said to be “a relaxing agent without causing sedation,” meaning it can help improve your ability to deal with stress without making you feel lethargic or tired.

If you suffer from nervousness, anxiety, depression, or other stress-related issues, you can likely benefit from L-theanine’s relaxing effects, although it likely won’t have a strong enough effect to reduce severe anxiety.

In one study, L-theanine was shown to reduce scores on a tension-anxiety test compared to a placebo. Both L-theanine and caffeine’s effects on mental task performance and physiological activities were investigated.

Participants were placed under conditions of physical or psychological stress, examining the effects of L-theanine. Results after the mental tasks showed that L-theanine significantly inhibited the blood pressure increase associated with stress, while caffeine tended to have a similar but smaller inhibition of blood pressure.

Theanine may also increase alpha brain waves (α-waves), which are associated with a state of “wakeful relaxation,” selective attention mechanisms, arousal, and mental alertness.

One study tested the effects of L-theanine on brain waves 45, 60, 75, 90, and 105 minutes after ingestion of 50 milligrams of L-theanine. The results showed that there was a greater increase in alpha activity across time in the L-theanine condition relative to the placebo.

According to the authors of the study, “These data indicate that L-theanine, at realistic dietary levels, has a significant effect on the general state of mental alertness or arousal. Furthermore, alpha activity is known to play an important role in critical aspects of attention, and further research is therefore focussed on understanding the effect of L-theanine on attentional processes.”

2. May Help Improve Sleep and Fight Insomnia

Why is L-theanine good for sleep? It helps reduce stress and anxiety, which can keep you up at night if you’re constantly worrying, tossing, and turning.

The effects that theanine has on sleep are mild, so it won’t work for every person to improve sleep quality. While it can have positive effects on sleep quality, it probably won’t be enough to help someone with moderate or severe insomnia to get a good night’s sleep.

L-theanine: Natural sleep aid for insomnia relief and improved sleep quality

Certain studies have found that L-theanine can help improve sleep quality in people with conditions that cause hyperactivity, including ADHD. Another positive attribute of L-theanine when it comes to sleep is that it can counter the effects of stimulants. This means that if you drink lots of coffee or use other stimulants for medical reasons, L-theanine’s calming effects may help reduce wakefulness, jitters, etc.

Some people choose to take L-theanine and melatonin together to help with sleep. A common dosage is around three milligrams of melatonin before bed taken with 100–200 milligrams of L-theanine. The two can act together to reduce stress and help with sleep quality, although L-theanine taken in high doses (above 600 milligrams) may have opposite effects — and so may melatonin.

3. May Help Improve Attention

Some people choose to use L-theanine and caffeine together in order to improve alertness, cognition, and attention. The two have a “synergistic” relationship and can lead to improved focus without feeling overly “wired” or jittery.

For this purpose, consuming about 200 milligrams each of L-theanine and caffeine tends to lead to the best results.

4. Can Help Protect Memory and Cognition

In one double-blind, placebo-controlled study, patients with mild cognitive impairment were given 360 milligrams of green tea extract along with 60 milligrams of theanine (a combination called LGNC-07) three times daily for 16 weeks. Researchers found that LGNC-07 helped improve recognition skills without having any negative effects on verbal and visuospatial memory.

Brain Boosters: Enhancing memory and cognition for a sharper mind

Study shows increased brain theta waves in temporal, frontal, parietal, and occipital areas after three hours of reading. Therefore, this study suggests that LGNC-07 has the potential as an intervention for cognitive improvement.”

L-theanine may protect the brain by preventing excessive glutamate stimulation, potentially linked to neurodegenerative disorders, stroke, and schizophrenia, through excitotoxicity. By blocking some of the glutamate’s effects, L-theanine may be able to offer neuroprotection for the aging brain.

5. May Help Support Cardiovascular Health

Green tea is a significant source of L-theanine, which has been shown to reduce inflammation and support heart health. Experts believe this is due to its anine content, rather than other active compounds like catechins or theaflavins.

Theanine may help to prevent blood pressure spikes in response to stressful events and help regulate nitric oxide. Nitric oxide aids communication, blood pressure regulation, inflammation reduction, immune system support, and sleep quality.

Nitric oxide in arteries relaxes narrowed vessels, increases oxygen flow. Adequate production of nitric oxide can help protect against artery-blocking clots or obstructions, heart attacks, stroke, and other cardiovascular problems.

L-theanine administration after stroke may protect brain cells and reduce damage.

Studies show anine supplementation in C. elegant roundworms can increase life span and longevity by 3.6-4.4 percent at high concentrations.

Researchers did not find that more theanine provided more benefits when it came to longevity. A dosage on the lower end of the range was actually the most effective.

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L-theanine vs. GABA

  • L-theanine can help to stimulate the production of the inhibitory, relaxing neurotransmitter called GABA.
  • GABA, like serotonin and dopamine, is known as a neurotransmitter. It helps regulate emotions, moods, concentration, motivation, and alertness. GABA can also affect sleep, appetite, and sex drive.
  • GABA is known to have calming, anti-anxiety effects, making it beneficial for lifting your mood and preventing nervousness or hyperactivity. Increasing GABA is one way that L-theanine has calming effects. L-theanine may reduce depression symptoms by elevating GABA and promoting appetite, sleep, and motivation.
  • Some anti-anxiety medications work by mimicking the effects of GABA, but these are commonly associated with drowsiness. L-theanine is attractive as a calming agent due to its ability to maintain motor skills without causing fatigue. In fact, it can increase alertness and promote relaxation at the same time.
  • Anine injections increase GABA concentrations in the brain, sometimes by 20%, while moderate doses mildly affect mood.

Risks and Side Effects

Is L-theanine safe? Research suggests that it is safest when used in the short term, for about several weeks to four months.

It is typically taken by mouth one time per day for about three to 16 weeks. It’s not clear if it is always safe or effective if taken for longer periods.

How much L-theanine is safe to take? Most people can safely consume 200-400 milligrams daily, divided into two to three doses, with higher doses also safe.

L-theanine can interact with certain medications, including those taken to control high blood pressure (called antihypertensive drugs) and stimulants. Avoid anine supplementation if already taking medications to lower blood pressure.

Examples of medications that lower blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), and diltiazem (Cardizem).

L-theanine disrupts stimulant effects by slowing nervous system activity. Consult a doctor before taking L-theanine if taking these drugs.

L-theanine can reduce caffeine and herbal stimulating effects in beverages like coffee, tea, and energy drinks.

Limited research on L-theanine safety during pregnancy suggests avoiding it, while green tea is generally safe for most women.

Dosage and Supplements

Because L-theanine is almost exclusively found in tea leaves, it can be hard to get enough from foods and drinks alone to notice its positive effects. This is why people turn to L-theanine in supplement form.

Theanine supplements generally come in the form of L-theanine, which is the bioavailable supplement form of the amino acid theanine. Suntheanine is a theanine supplement made with a patented fermentation process. Sun-theanine manufacturers claim potency, but efficacy and tolerance are similar in L-theanine and sun-theanine quality.

Where to Find and How to Use L-theanine:

Theanine supplements come in different forms, including capsules, pills, and tablets. To ensure you’re buying a quality product, always check the ingredients in the supplement formula. Purchase a supplement that is pure theanine/L-theanine and does not have fillers or other chemicals.

Keep in mind that some energizing theanine formulas may include caffeine, which would not be beneficial to reducing anxiety or helping with sleep.

  • L-theanine is typically taken in a dosage of 100–200 milligrams per day. It can be taken along with caffeine but doesn’t need to be.
  • The calming effects of L-theanine usually kick in within about 30–60 minutes after taking it.
  • To help treat insomnia, ADHD, and hyperactivity, doses of 200 milligrams taken twice daily are usually the most effective.
  • Higher doses of L-theanine, around 400 milligrams, may be used to help manage symptoms of schizophrenia or severe anxiety disorders. This dose may be used for up to eight weeks.
  • For help with reducing anxiety, a combination of L-theanine (400 mg per day) and the hormone pregnenolone (50 mg per day) is sometimes used.

Can you take L-theanine on an empty stomach? Yes, L-theanine can be taken either with meals or on an empty stomach.

Consuming L-theanine without eating may cause more intense and rapid effects, similar to caffeine consumed with a meal. If you’re using L-theanine to help you sleep, try taking it about 30–60 minutes before bed.


Is L-theanine natural? Yes, it’s found in certain foods and beverages, including green tea (made from the leaves of the camellia sinensis plant).

Along with caffeine and catechins, L-theanine is one of the main active ingredients found in green tea. Theanine is believed to give green tea its umami flavor and counteract bitter taste in tea and other foods.

How much L-theanine is in green tea? It comprises up to 50 percent of the total amino acids in tea.

About 0.9 percent to 3.1 percent of the dry weight of green tea leaves is theanine. This equates to about 25 to 60 milligrams of theanine per 200 milliliters of tea, or about 6.7 ounces. This amount of tea is typically made from about 2.5 grams of dried tea leaves.

Theanine content in green tea varies depending on the specific type of tea. Teas made from younger plants have higher theanine content than teas made from older plants. Theanine content is also reduced from fermentation (part of the process used to make tea leaves), but it becomes more concentrated when leaves are dried.

Other plants that provide L-theanine include:

  • C. japonica and C. sasanqua — These are small shrubs that produce pink and red flowers. They are sometimes used to make tea, although not as commonly as camellia sinensis. (12)
  • Xerocomus badius, also known as bay bolete, is a brown, edible, pored mushroom found in Europe and North America.

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Final Thoughts

  • L-theanine (or simply theanine) is a nondietary amino acid that is found in green, black, and white teas, plus can be taken in supplement form.
  • L-theanine has relaxing properties, improving focus, attention, sleep, heart, brain, and blood pressure regulation, and reducing schizophrenia symptoms without drowsiness.
  • Drinking quality green tea daily is the best natural way to obtain L-theanine.
  • L-theanine is safe supplement form, reduces blood pressure medication effects, and can be combined with caffeine for focus improvement.

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