L-Theanine: Get More Zen

L-Theanine: Get More Zen

CrossFit Sleep Supplements

I first came across L-theanine several years ago when I was doing some research on nootropics. Nootropics are supplements that are meant to help with brain function, particularly focus and concentration. I was working on my doctorate and looking for ways to help me grind through my study sessions more efficiently.

The world of nootropics is not far removed from the world of sleep supplements. Partly because sleep is a brain function. Partly because when you're learning about how to get your brain to work better, you quickly learn that good sleep is not negotiable.

L-theanine is relied on as a brain supplement for a variety of reported benefits. One is that it helps to take the edge off of stimulants. It often gets stacked with caffeine, helping to achieve an alert but calm state, without the jitters that caffeine can bring. It also has its own strengths in helping support focus, concentration, and learning.

These days, I rely on L-theanine much more for hacking my sleep than for hacking my studying. L-theanine is a big player in the sleep game for its ability to promote calm and support good sleep quality.

What is L-theanine?

L-Theanine, is an amino acid. It is found in tea leaves and some types of mushrooms.  It makes up 1-2% of the dry weight of tea. Black and green tea are the main dietary sources of L-theanine. It is also available in supplement form. For supplements, L-theanine is made using a fermentation process. We include it in our PM Recovery Collagen

Here's why:


One of the keys to easing into a good night's sleep is being able to calm your mind.  L-theanine has been shown to help with managing stress and anxiety. A 2017 scientific review that rounded up 49 studies involving green tea and L-theanine supplements taken by people, not animals, reported that there was a significant effect found using l-theanine alone for "improved self-reported relaxation, tension, and calmness (3)."

A 2016 study at a university in Australia measured self-rated stress levels as well as cortisol (stress hormone) levels  and brain waves of healthy volunteers who were given either a placebo or a drink with L-theanine in it. They then asked the participants to perform a stressful cognitive task (5). The L-theanine drinkers reported stress levels were significantly less than the placebo group after one hour. After 3 hours, the L-theanine group had significantly decreased cortisol levels compared to the placebo group (5). Another interesting finding from this study was an increase in alpha brain waves. This increase happened in the L-theanine drinkers, but was only significant in participants who had previously identified themselves as having a tendency towards anxiety. Alpha waves are calm brain waves that increase during meditation and during REM sleep.

Reviews of published research data suggest that L-theanine taken daily in amounts ranging from 200 to 400 mg is safe and "induce anxiolytic (anxiety reducing) and anti-stress effects in acute and chronic conditions (4)."

Though more research is needed to understand exactly how L-theanine affects the brain, there is data to show that it has effects on brain chemistry. L-theanine  has been shown to boost levels of GABA, serotonin, and dopamine (8).  GABA is a brain chemical in the brain that is primarily responsible for calming and relaxing your brain and nervous system. It counteracts  brain chemicals that are excitatory. Serotonin is a brain chemical that helps with stabilizing your mood and feeling happy. Dopamine is a brain chemical also involved in mood regulation and plays a big role in your ability to feel pleasure and motivation.  Supporting healthy levels of these brain chemicals improves your ability to be calm, happy, and have a general sense of well being.

Sleep quality

L-theanine not only supports the activity of the calm and happy brain chemicals, it has also been shown to counter the activity of the excitatory chemicals in the brain. This is linked to better sleep quality (7).

In order to fall asleep, your brain and body need to be calm. GABA is a key player in the transition from being awake to being asleep.  For you to stay asleep and have good quality sleep, the your stress response system needs to stay quiet and your brain needs to be able to transition between different types of brain waves and phases of light, deep and REM sleep without being interrupted. Studies have shown that L-theanine promotes alpha waves in the brain which indicates a calm and creative state and is also an important feature of REM sleep (5,7). It also helps decrease beta waves (7). Beta waves occur when the brain is actively engaged in mental activities, it is a sign of waking up.

Studies conducted in Japan studying the effect of L-theanine on sleep have shown improved the quality of sleep, improved dream quality, improved feeling of recovery from exhaustion or fatigue, improvement in a refreshed feeling upon awakening, and less intermittent awakening in the night (7).

A 2019 study looking at the effects of taking GABA and L-theanine at the same found a decrease in time to fall asleep and an increase in time spent sleeping compared to not taking anything (placebo) or taking either supplement on their own (2).

How to take L-theanine

L-theanine can be taken on its own or in combination with other supplements. It is not shown to have negative side effects and it is not a sedative. Its ability to support a calm and relaxed state with out a sedative effect is one of the reasons why we love L-theanine so much. It's great before bed, but can also be taken during the day.

Typical dosing is 200 - 400 mg and it starts to work in 30 - 40 minutes.

As bedtime support, take it 30 - 60 minutes before bedtime. Our Thirdzy PM Recovery Collagen formula has 200mg of L-theanine per serving along with GABA, magnesium, L-tryptophan and collagen, which all work together to support great sleep and recovery.

Sleep tight,
Dr. J

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*** The views expressed in this article are those of one expert. They are the opinions of the expert and do not necessarily represent the complete picture of the topic at hand. This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.


  1. Kimura K, Ozeki M, Juneja LR, Ohira H. L-Theanine reduces psychological and physiological stress responses. Biol Psychol. 2007 Jan;74(1):39-45. doi: 10.1016/j.biopsycho.2006.06.006. Epub 2006 Aug 22. PMID: 16930802.
  2. Kim, Suhyeon, et al. GABA and l-theanine mixture decreases sleep latency and improves NREM sleep. Pharmaceutical biology 57.1 (2019): 64-72.
  3. Dietz C, Dekker M. Effect of Green Tea Phytochemicals on Mood and Cognition. Curr Pharm Des. 2017;23(19):2876-2905. doi: 10.2174/1381612823666170105151800. PMID: 28056735.
  4. Lopes Sakamoto F, Metzker Pereira Ribeiro R, Amador Bueno A, Oliveira Santos H. Psychotropic effects of L-theanine and its clinical properties: From the management of anxiety and stress to a potential use in schizophrenia. Pharmacol Res. 2019 Sep;147:104395. doi: 10.1016/j.phrs.2019.104395. Epub 2019 Aug 11. PMID: 31412272.
  5. White DJ, de Klerk S, Woods W, Gondalia S, Noonan C, Scholey AB. Anti-Stress, Behavioural and Magnetoencephalography Effects of an L-Theanine-Based Nutrient Drink: A Randomised, Double-Blind, Placebo-Controlled, Crossover Trial. Nutrients. 2016 Jan 19;8(1):53. doi: 10.3390/nu8010053. PMID: 26797633; PMCID: PMC4728665.
  6. Williams JL, Everett JM, D'Cunha NM, Sergi D, Georgousopoulou EN, Keegan RJ, McKune AJ, Mellor DD, Anstice N, Naumovski N. The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review. Plant Foods Hum Nutr. 2020 Mar;75(1):12-23. doi: 10.1007/s11130-019-00771-5. PMID: 31758301.
  7. Rao, Theertham P., Motoko Ozeki, and Lekh R. Juneja. "In search of a safe natural sleep aid." Journal of the American College of Nutrition 34.5 (2015): 436-447.
  8. Nathan PJ, Lu K, Gray M, Oliver C. The neuropharmacology of L-theanine(N-ethyl-L-glutamine): a possible neuroprotective and cognitive enhancing agent. J Herb Pharmacother. 2006;6(2):21-30. PMID: 17182482.

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