Does L-Theanine help with Sleep, Anxiety and Stress?
By Human Window
Updated on January 30, 2019
Fact Checked This article was fact checked by one of our writers on November 05, 2018.

L-Theanine is an amino acid which is primarily found in tea leaves. It is not commonly found in the diet and is therefore considered as something called a “non-dietary” amino acid.

It’s one of the active ingredients found in Green Tea, and it is often used as an ingredient in modern food supplements.

L-Theanine is claimed to have a number of benefits, including helping to induce relaxation and possibly helping with sleep.

But what does the science say about L-Theanine’s effects, and is it a supplement you should consider taking to help with Sleep, Anxiety and Stress?

The purpose of this article is for us to take an evidence-based look at L-Theanine to see whether it can live up to the hype it has been getting in the supplement industry recently.

We’re going to break the article into the following sections:

• What is L-Theanine?
• Does L-Theanine help with Sleep?
• Does L-Theanine help with Anxiety?
• Does L-Theanine help with Stress?
• Other L-Theanine Benefits
• What’s the Best Dose of L-Theanine?
• Anything Else To Consider?
• Conclusion

So, let’s begin our close look at L-Theanine by finding out a bit more about this amino acid.

What is L-Theanine?

As we’ve already mentioned in our introduction above, L-Theanine is an amino acid which is primarily found in tea leaves. It’s found in high amounts in green and black tea.

It is a non-dietary amino acid, meaning that your body doesn’t need it to be able to function normally, but supplementing with it could bring some benefits.

Some research indicates that L-Theanine could promote relaxation without drowsiness. For this reason, it is often combined with Caffeine in some pre workout supplements, to help induce a feeling of calm while boosting energy levels.

The same study linked to above suggests that L-Theanine can help to promote the release of alpha brain waves in young adult males. Alpha brain waves are related to mental relaxation and concentration.

So to summarize, L-Theanine is as a relaxing but not sedating amino acid which is a common ingredient in food supplements.

But what about the other potential and claimed benefits of L-Theanine? Let’s focus on those in a bit more detail now.

Does L-Theanine help with Sleep?

If you’re wondering whether L-Theanine helps with Sleep, there is some initial evidence to suggest that it can.

Although L-Theanine does not appear to induce sleep itself, there is some evidence to suggest that it could help to improve sleep quality.

One study from 2011 concluded that supplementing with 400mg of L-Theanine every day helped to improve some aspects of sleep quality in boys diagnosed with Attention Deficit Hyperactivity Disorder (ADHD).

The same study noted a significant improvement in sleep efficiency over the course of the trials, which lasted for six weeks.

As well as the above study in humans, one animal study found that L-Theanine partially counteracts caffeine-induced sleep disturbances in rats.

The bottom line here is that there is some evidence that L-Theanine could help to improve sleep quality, but more research is probably needed before drawing concrete conclusions.

Does L-Theanine help with Anxiety?

There is some limited initial evidence to suggest that L-Theanine could help with anxiety.

One study noted that people with high baseline anxiety levels noted benefits from supplementing with L-Theanine.

Another study from 2011 found that L-Theanine seemed to decrease anxiety and improve symptoms in people with schizophrenia or schizoaffective disorder.

There is also the main study from 2016 which showed that L-Theanine can help increase relaxation without causing any drowsiness.

The bottom line here is that L-Theanine could help with anxiety, although the evidence suggests it is likely to be more effective in people who already suffer from high baseline levels of anxiety.

Again, more research is needed before drawing any concrete conclusions.

L-Theanine is an amino acid found in Green Tea (Photo: Adobe Stock)
L-Theanine is an amino acid found in Green Tea (Photo: Adobe Stock)

Does L-Theanine help with Stress?

As well as the claimed anti-anxiety benefits we’ve already mentioned above, there is also some evidence that L-Theanine could help with stress.

One study from 2007 concluded that oral intake of L-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.

There has also been a study on rats which showed that oral supplementation of L-Theanine helped to reduce the circulating biomarkers of stress.

So, L-Theanine has also shown promise at being able to potentially help with stress. More research is needed, though.

Other L-Theanine Benefits

As well as the three main potential benefits we’ve touched on above, it has been claimed that L-Theanine could also help to improve focus and concentration when paired with Caffeine.

One recent study found that combining L-Theanine with Caffeine helped to improve cognitive performance subjective alertness.

This is why L-Theanine and Caffeine are often combined together in the same supplement, most commonly in pre workouts which are designed to be taken before exercise.

What’s the Best Dose of L-Theanine?

There is currently no official recommendation for best dose of L-Theanine.

However, L-Theanine is most commonly taken at doses of around 100mg to 200mg, and as we mentioned above, it’s often combined with Caffeine.

You should always consult your doctor before taking any new supplement for the first time.

Anything Else To Consider?

Clearly, L-Theanine has shown promise at being able to help with a range of different things, including Sleep, Stress and Anxiety.

However, you should always remember that there is no miracle supplement out there to solve all of your problems.

Making sure that you are living a healthy life, eating a balance diet and getting plenty of exercise and rest should always be your first ports of call before considering any kind of supplementation.

As we mentioned above, you should always first consult your doctor before trying any new supplement or health product for the first time.

Although L-Theanine is generally considered to be safe, you should always do some of your own research and consult your doctor before considering taking it.


That brings us to the end of our article looking at whether L-Theanine helps with Sleep, Anxiety and Stress.

We’ve walked you through the basic facts about L-Theanine as a non-dietary amino acid which is found primarily in tea leaves.

We’ve also looked at some of the initial scientific studies which suggests that L-Theanine could indeed help with things such as Sleep, Anxiety and Stress – although more research is needed.

L-Theanine has also been shown to potentially increase relaxation without causing drowsiness or sedation in some studies.

It has also shown promise at helping to promote alertness and concentration when paired with Caffeine, which is why you’ll find these two substances in many of the leading pre workout supplements on the market at the moment.