L-Theanine and Sleep

l-theanine sleep supplement

Sleep is an extremely complex process.  High quality L-Theanine has been proven to help improve the overall quality of sleep. L-theanine as a sleep supplement has an added benefit because it’s generally considered non-addictive or habit-forming. When taken during the day, it is non-drowsy and helpful for improving focus and mood. When taken before bedtime, it is quite helpful for improving sleep quality and reducing sleep latency (the time it takes to fall asleep).

How does L Theanine improve sleep quality?

L Theanine increases alpha brain wave activity. Alpha brain waves are mainly known to be present during 2 phases.

One time alpha brain wave activity is high is when a person is in a deep state of mental relaxation. This is when their eyes are closed, but they are neither drowsy nor sleeping. This is a very deep state of mental relaxation – a state which masters of Zen Buddhism are able to reach.

The other time alpha brain wave activity is high is during REM (rapid eye movement) sleep. REM sleep is one of the 5 phases of sleep, and it’s often regarded as the most important phase. Measuring the total amount of time a person sleeps is less important than measuring the quality of a person’s sleep. L theanine is well-known for improving a person’s sleep quality, not just making someone sleep longer. Generally speaking, the more REM sleep a person has, the better the quality. The person taking L-theanine will wake up feeling well rested and alert, not tired and groggy the next morning. We’ll get to the specific scientific studies on this below.

Another significant way L Theanine works to improve sleep is the effect it has on the inhibitory neurotransmitter GABA. The more GABA in the brain, or the more efficiently GABA is working, the better the sleep quality. GABA is an anxiolytic (anti-anxiety) neurotransmitter. By increasing the effectiveness of the GABA system, L Theanine works to quiet the mind, slow down racing thoughts, and prepare it to drift off into a deep and peaceful sleep.

alpha brain waves calm down with l-theanine

L Theanine has also been scientifically shown to reduce the edgy or jittery effects from caffeine. So if you are wondering how to counteract or neutralize the effects of caffeine, L Theanine can be a great antidote. And if you drink tea, coffee, cola, or anything caffeinated in the afternoon or evening, L Theanine is a wise choice to help you with your sleep.

Caffeine stays in the system for a long time and the effects can last up to 14 hours. So if you have caffeine at noon, it could still be affecting you by 2 am!

L Theanine has also been scientifically shown to reduce the edgy or jittery effects from caffeine. So if you are wondering how to counteract or neutralize the effects of caffeine, L Theanine can be a great antidote. And if you drink tea, coffee, cola, or anything caffeinated in the afternoon or evening, L Theanine is a wise choice to help you with your sleep.

Caffeine stays in the system for a long time and the effects can last up to 14 hours. So if you have caffeine at noon, it could still be affecting you by 2 am!

Check out are article here on l theanine and caffeine taken together.

The Science behind L Theanine and Sleep:

Here are a few interesting scientific studies which show L Theanine’s benefits for improved sleep quality.

Study 1:

This study is a direct measurement of alpha brain wave activity from taking L Theanine vs a placebo. We know that alpha brain wave activity is very high during deep meditative states of relaxation, and also during high quality REM sleep.

The study aimed to show that low levels of L Theanine (50mg per day) were enough to produce significant results. The reason they chose such a low amount of L Theanine to study was to see if a realistic dietary intake of L Theanine is enough to make a difference. L Theanine is found naturally in green tea, about 20 mg’s per cup.

l-theanine from grean tea

The results were such that even 50 mg of L Theanine was enough to significantly increase alpha brain wave activity in subjects resting with their eyes closed, and also when performing moderate activity. There is significant evidence that higher levels of L Theanine (125-250 mg per day) produce even more significant results.

Here is a link to the study

Study 2:

This study reviewed the mechanism of L-theanine as a natural sleep aid. It suggests that taking 200 mg of L-theanine before bed improves sleep quality by reducing anxiety rather than sedation.

The study also suggests that L-theanine does not cause daytime drowsiness and has no observable adverse effects at recommended doses. Overall, the study concludes that L-theanine is a safe and effective natural sleep aid, which is non-addictive and has very few side effects.

L-theanine has the added benefit of not causing drowsiness when taken during the day, or causing drowsiness the morning after taking it.

Study 3:

Here was a recent crossover study that looked at several benefits of l theanine compared to placebo.  They gave participants 200 mg of l theanine or an identical looking placebo. 

The way they measured sleep was assessed using the Pittsburgh Sleep Quality Index (PSQI). 

They concluded:

“The reduction in sleep quality problems (disturbances in sleep latency, sleep disturbance, and use of sleep medication) was greater in the L-theanine administration compared to the placebo administration”

Study 4:

Another double blind study looked at subjects with general anxiety disorder.  They took relative high dose l theanine (450 – 900) mg per day, along with their current antidepressant medication.  

One conclusion of the study was:

Participants treated with l theanine “reported greater self-reported sleep satisfaction than placebo”


This means that people woke up feeling better and more well-rested after taking L-theanine. The study also showed that even relatively high doses of L-theanine are quite safe and well tolerated.

Study 5:

This double blind study looked at boys, aged 8 – 12 years old, with ADHD.  

They took 200 mg of l theanine (twice daily) or a placebo. 

The study results showed that:

“Actigraph watch data findings indicated that boys who consumed L-theanine obtained significantly higher sleep percentage and sleep efficiency scores”

Overall insights from the studies on L-theanine and sleep:

These studies are great to view in conjunction with one another.

The first study shows that L Theanine actually increases alpha brain waves on a physical level, which would indicate a better sleep from more time in REM sleep, explain the potential for fewer nightmares, and also predict a better state of mind before drifting off to sleep. This is all due to what we know about increased alpha brainwave activity. See above.

The second study showed that L-theanine works by reducing anxiety, rather than as a sedative. This is beneficial by not causing drowsiness when taken during the day, and by not being addictive.

The third study showed that L-theanine improved sleep quality by reducing sleep latency, reducing sleep disturbances, and decreasing the need for other sleep medications.

The final 2 studies indicate that l theanine can be useful as an adjunct sleep therapy, even in patients who have conditions that would typically make them more likely to have sleep problems (eg. people with general anxiety disorder or boys with ADHD)

What is an ideal dose when using L Theanine for sleep?

Stating the absolute right dose of L Theanine for sleep is impossible to say with 100% certainty. It’s not a “one size fits all” type of thing, and this depends on many factors. The way doses are normally recommended is based from the relatively few studies done on the subject. What we do know is that even doses as low as 50 mg per day could have a significantly positive effect on sleep. More studies on L Theanine and sleep have looked at doses in the range of 200-250 mg per day. Some studies, as mentioned above, even go up to 900 mg per day (This is a much higher than normal dose, but it does help to indicate that l theanine is safe and well tolerated)

Generally speaking, we recommend a dose of 250 mg per day of L-Theanine for sleep.

How to find high quality L-theanine:

l theanine molecule

Not all L-theanine is the same. There are a few things you need to look out for in terms of finding quality. One thing is the purity of L-theanine. Did you ever wonder what the “L” is?

There are actually 2 types of theanine molecules. There is “L” theanine and “D” theanine. These are isomers of each other. That means they are almost the same molecule, but one is “backwards”. It is like trying to fit a left-handed glove on your right hand.  It won’t work no matter how you rotate the glove.

You want to make sure that the L-theanine you buy is over 99% pure. That means it is over 99% “L” theanine and under one percent “D” theanine. If a product says “L” theanine on the label, it doesn’t mean that it is pure. Cheaply made L-theanine can easily be a “racemic” solution, which is a compound containing very high amounts of D-theanine.

You need to trust your manufacturer. Just looking at a nice looking, clean powder won’t tell you all you need to know.

l-theanine powder

Where to buy high quality l theanine for sleep?

We use a pharmaceutical grade l theanine that has been a huge hit with our customers all over the world. It is over 99% in purity in terms of the “L” isomer. We use pure veggie caps and no unhealthy fillers like magnesium stearate. Quality is everything to us. If we were unable to find something of excellent quality, then we wouldn’t bother releasing the product at all.

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Andrew Best

Cofounder - Director of R&D

Andrew educates consumers about the latest scientific research in the natural health supplement field.

Author Bio

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