How Long for L-Theanine to Start Working?

Updated on September 18, 2023
 by — reviewed by Jason Williams, PhD (Contributor: George Collins / Editor: Yoko Hill)
how long does it take for l-theanine to help anxiety

How long for L-Theanine to start working?

Are you looking for a natural way to reduce stress and anxiety? 

Look no further than L-Theanine. 

This amino acid has gained popularity for its potential to promote relaxation and improve focus. But just how long does it take for L-Theanine to start working?

In this article, we will explore the factual data to answer this question and provide you with valuable insights on incorporating L-Theanine into your daily routine for maximum benefits.

So, let's dive in and discover how L-Theanine can help you find peace and clarity in a fast-paced world.

Understanding L-Theanine and Its Effects 

L-Theanine is a unique amino acid found in green tea that has gained popularity for its numerous health benefits. This amino acid is a key component in green tea, giving it a distinct flavor.

In addition to its taste-enhancing properties, L-Theanine has been found to have a range of health benefits, including: 

  • Reduce Stress and Anxiety: One of the main benefits of L-Theanine is its ability to promote relaxation and reduce stress and anxiety. Several studies have shown that L-Theanine can help reduce stress and anxiety in people facing stressful situations.(1) It can also improve symptoms in individuals with schizophrenia or schizoaffective disorder.
  • Improve Sleep Quality: L-Theanine may also help improve sleep quality by promoting relaxation and reducing insomnia. Studies have shown that L-Theanine can help people relax before bedtime, fall asleep more easily, and experience more restful sleep.(2)
  • Enhance Cognitive Function: L-Theanine has been found to have cognitive benefits, including improving attention, focus, and reaction times.(3).
  • Boost Immune System: L-Theanine may help improve the function of the body's immune system, making individuals less susceptible to upper respiratory tract infections and the flu.(4) It has also been associated with improving inflammation in the intestinal tract.
  • Potential Anti-Tumor Effects: L-Theanine has been linked to amplifying the anti-tumor effects of certain chemotherapy drugs. This suggests that it may help improve chemotherapy's ability to fight cancer.(5) However, more research is needed to fully understand its effectiveness in this area.
  • Lower Blood Pressure: L-Theanine may be beneficial for those who experience increased blood pressure in stressful situations. Studies have shown that it can help reduce blood pressure in individuals who typically experience higher blood pressure after specific mental tasks.(6)
  • Aid Weight Loss: L-Theanine, especially when consumed in green tea, can aid weight loss by reducing appetite. The umami flavor created by L-Theanine can help decrease food cravings, making it easier to stick to a calorie-controlled diet.
  • Enhance Sleep in ADHD: L-Theanine has been found to improve sleep quality in boys diagnosed with attention deficit hyperactivity disorder (ADHD). It can lead to longer and more restful sleep, although more research is needed to determine its safety and effectiveness, especially for children.

The content of L-Theanine in tea can vary depending on factors such as tea category, genetic background, temperature, season, and growth period.

Different categories of tea have different levels of L-Theanine, and the content of L-Theanine changes as the tea leaves mature.

Therefore, getting L-Theanine from green tea is not the best way to get regulated daily doses of this functional amino acid.

So, what's the best way to take L-Theanine?

The best way to take this natural nootropic is by adding premium-quality and regulated L-Theanine supplements to your wellness routine.

These are capsules that are easily taken orally with a glass of water. The dose of L-Theanine within each of the capsules is regulated and allows you to consistently get the best of its benefits.

Overall, L-Theanine is a remarkable amino acid with numerous health benefits. Its unique properties make it a valuable substance with a remarkable impact on the development of functional foods.(7)

How L-Theanine Works in the Body

L-Theanine has been recognized for its remarkable effects on mental states.

Once it crosses the blood-brain barrier, L-Theanine alters the levels of amino acids that have a direct impact on neurotransmitters like serotonin, dopamine, and gamma-aminobutyric acid (GABA).

This modulation of neurotransmitters is what contributes to the profound effects of L-Theanine on mental well-being.

Research has shown that L-Theanine significantly increases alpha activity in the brain, which is associated with a relaxed and alert state of mind.

This effect has been observed in studies where participants consumed higher doses of L-Theanine than what is typically found in a cup of tea. However, recent research aimed to establish the same effect at more realistic dietary levels and found that even at lower doses, L-Theanine has a significant impact on mental alertness and arousal.

In addition to its effects on brain waves, L-Theanine also acts upon GABA and glycine receptors, triggering increased levels of serotonin and dopamine in select brain regions.

This mechanism further contributes to the calming and mood-enhancing effects of L-Theanine.

One study conducted in South Korea demonstrated that tablets containing L-Theanine promoted the release of alpha brain waves associated with mental relaxation and concentration.

Another study conducted in Japan showed that L-Theanine reduced heart rate and stress-induced immunoglobulin A (s-IgA) levels, indicating its ability to counteract the effects of acute stress.

L-Theanine's ability to balance brain chemistry and improve cognitive health is also associated with its impact on attentional processes. Alpha brain wave activity, which is increased by L-Theanine, plays a crucial role in attention and focus.

Overall, L-Theanine's impact on neurotransmitters, brain waves, and attentional processes contributes to its calming, mood-enhancing, and cognitive benefits!

How Long Does it Take for L-Theanine to Work?

L-Theanine typically begins to work within 30 minutes after intake. The duration of its effects can extend up to 8 to 10.

It's advised to start with a daily dose of 100 milligrams, which can be increased up to a maximum of 400 milligrams per day for managing stress or anxiety.

Factors Influencing the Onset of L-Theanine

Several factors can influence how quickly L-Theanine starts working in the body, such as

  1. Dosage: The dosage of L-Theanine taken can affect the onset of its effects. Higher doses may result in more immediate and noticeable effects, while lower doses may take longer to take effect. The recommended dosages range from 100-400 mg, with a maximum of 1200 mg per day.
  2. Weight: Body weight can also play a role in how quickly L-Theanine starts working. Individuals with a higher body weight may require a higher dosage to achieve the desired effects.
  3. Metabolic Rate: Metabolism can impact how quickly L-Theanine is processed by the body. Individuals with a faster metabolism may experience the effects of L-Theanine more quickly, while those with a slower metabolism may require more time.
  4. Meals: Taking L-Theanine on an empty stomach may lead to faster absorption and onset of effects compared to taking it with food. However, some individuals may prefer taking it with food to avoid potential stomach discomfort.
  5. Caffeine Intake: Taking L-Theanine in combination with high-quality caffeine pills can also influence its onset. Caffeine has stimulatory effects that can enhance the effects of L-Theanine and potentially expedite its onset. This is one of the best natural nootropic stacks for those with ADHD.

Overall, these factors should be taken into consideration when using L-Theanine to determine the optimal timing and dosage for the desired effects.

It is recommended to start with a lower dosage and gradually increase as needed to assess individual response and tolerance levels. 

Signs That L-Theanine is Working

Here are some signs and symptoms that indicate L-Theanine is working:

  • Reduced Stress: One of the primary benefits of L-Theanine is its ability to reduce stress and anxiety. When L-Theanine starts working, you may notice a decrease in feelings of stress and an overall sense of relaxation.
  • Improved Focus: L-Theanine has been shown to enhance focus and attention, especially when paired with caffeine. If you find that your concentration and cognitive abilities improve after taking L-Theanine, it indicates that it is having a positive effect on your focus.
  • Better Sleep: L-Theanine has been found to promote better sleep quality. If you experience improved sleep patterns, fall asleep faster, or wake up feeling more refreshed after taking L-Theanine, it suggests that it is positively impacting your sleep.
  • Calmness: L-Theanine is well-known for inducing a sense of calmness and relaxation without causing drowsiness. If you feel more at ease and less restless or agitated after taking L-Theanine, it means that it is effectively promoting a state of calmness in your body.

It's important to note that individual responses to L-Theanine may vary, and it may take some time to notice the effects.


Many people turn to L-Theanine to reduce stress, improve mood, and enhance cognitive function. But how long does it take for L-Theanine to start working?

Based on research, the effects of L-Theanine are typically felt within the first 30 minutes of ingestion. These effects can last for up to 8 to 12 hours.

However, individual experiences may vary, and it's essential to understand that factors such as metabolism, body weight, and overall health can influence how quickly L-Theanine takes effect.

Whether you're looking to reduce stress, improve sleep, or enhance cognitive function, L-Theanine supplements can offer promising results. 

As always, consulting with a healthcare professional is recommended before starting any new supplement regimen.