You are restless, anxious, nervous, distracted; it is late at night and you just can’t sleep. Have a cup of tea. You drank four cups of coffee before a big exam and now you can’t concentrate on anything because you keep shaking and your head hurts. Drink a cup of tea. If modern studies are true, tea might actually act as an anti-anxiety, anti-stress compound, with sedative qualities and the ability to help you focus on the task at hand. Have we found the new non-prescription miracle drug for all the world’s ills? That might be a stretch, but my recent investigation suggests that we need to rethink the idea of caffeine content in tea, and make room for a more complex treatment of tea than caffeine levels measured in milligrams.

My investigation began with a contemplation of the concept of chaqi (chah-chee). In China, my tea mentors often talk about this mysterious chaqi.  This idea is based in a very different concept of wellness related to the flow of vital energies through the body.  A tea with good chaqi is said to promote this flow of energy, and enhance spiritual attainment to the sensory experience of tea drinking, promote heightened contemplation and meditation, etc.  When you ask what causes this feeling and how exactly it effects the body, there is a lot less clarity.

I asked my mentors if chaqi is the same thing as caffeine, and they emphatically denied that possibility.  Caffeine can be found in soda, coffee, etc, but there is a very specific feeling of alertness that many claim only tea can bring about. Is there something about tea that gives it special calming and sedative effects that other caffeinated beverages lack?  For the longest time, I thought that it was just the ritual of sitting down and sipping tea that produced the psychological effect of well-being.  The social interaction of a tea tasting ceremony may actually raise levels of seratonin in the brain.   If this is the case, then it made sense to me that even consuming a caffeinated beverage could have a calming effect in the right social context.

While the social context is important, and the reduced stress and anxiety of tea drinking in a group cannot be ignored given the medical proof that such activity may in fact make you happier, that couldn’t be the whole story.  I feel great even when I drink tea by myself, even if the calming effects are not as strong.  To further this investigation, I looked into what chemical compounds tea has that other foods and beverages do not seem to contain at the same levels.

The most intriguing thing I found that is the role of a complimentary compound in tea separate from caffeine: L-theanine.  A 2012 study showed promising results indicating that while the alertness you get from caffeine is not diminished by L-theanine, you sleep more solidly and less fitfully when you drink tea (which contains L-theanine and caffeine) than you would from a beverage that contains only caffeine (like coffee).  This study was conducted by measuring slow-wave sleep in rats.  Caffeine dramatically reduced slow-wave sleep while a combination of L-theanine and caffeine counteracted this decrease significantly.  Tea is one of the most common substances in which both caffeine and L-theanine occur naturally.

Another study in 2012 was conducted with human volunteers which measured brain wave patterns of participants administered caffeine, L-theanine, both and neither.  Only those administered with both caffeine and L-theanine together showed an increase in brain wave activity, and a decrease in error rate on sustained monotonous activity.

Another study in 2010 compliments the findings of the 2012 experiment by measuring cognitive performance, mood, and blood pressure with caffeine, L-theanine, and both together.  The group given both caffeine and L-theanine showed significantly higher accuracy and reported much lower levels of tiredness, and higher levels of alertness than either group given one compound or the other.  Caffeine and L-theanine seem to work together, enhancing the good effects of alertness and sustained attention while working synergistically to reduce the negative effects of fitfulness and restlessness commonly felt in caffeine.  Tea was often used in early history by monks practicing meditation as an aid to concentration.  It appears that modern studies confirm that tea uniquely boosts cognitive function without the same level of caffeine-induced overactivity.

In fact, people suffering from anxiety, restlessness and overstimulation may benefit by drinking tea to produce a greater sense of calm and focus if these recent studies hold true.

Lab tests also introduce the possibility that the polyphenol EGCG present in tea may actually act as a sedative, counterbalancing the stimulant quality of caffeine.  EGCG administered to chicks lowered social separation stress and increased sleep by interacting with the GABAA receptors in the brain.  The same effect was observed in mice in a 2006 study indicating that the powerful anti-oxidant EGCG found in tea may actually directly work to counteract the stimulant properties of tea’s naturally occurring caffeine.

The balance of the synergistic alertness-boosting, anxiety-reducing effects of caffeine and L-theanine combined with the mild sedative effect of EGCG antioxidants may in fact be the answer to our search for chaqi.  Of course, the Chinese concept of chaqi is holisitc, and takes the social act of tea drinking, and enforced meditation into account, but in our search for the chemical contributors to chaqi, this is the strongest case I have seen so far that can be applied to any kind of tea, from green tea to pu’er.

The important lesson to take away from this is that as a tea buyer you should pay more attention to a tea’s specific effect on your body than to the stated caffeine content.  A tea might be very high in caffeine, but also high in EGCG and L-theanine, which in the end may contribute to a more calming effect than a stimulant effect.  Predicting the exact effect a tea is going to have becomes more complex task than measuring caffeine.

Generally it seems that black teas have been measured to contain more L-theanine than green tea, but the question to be asked is which black teas? A tea bag is very different from looseleaf Yunnan black, or Fujianese black, or even a Darjeeling or Assam.  No conclusive evidence can be presented on the most EGCG-rich teas either.  It all depends on processing technique, region, and more.  A 2010 study that attempted  a more comprehensive sampling of white and green teas from different regions found great overlap in the amount of EGCG antioxidants in each, dismissing the idea that green tea is king for antioxidant levels.  This also means that we are going to have an even harder time mapping the physiological effects of a tea, or predicting the chaqi until we just give it a try.

All of this investigation has helped me to better understand what an incredibly complex plant tea is.  In addition to the almost infinite synergistic effects of flavor, texture, aroma, and aftertaste, it seems that the physiological possibilities for tea are just as rich.  Unless you are extremely sensitive to caffeine, don’t be afraid to experiment with different kinds of tea and different brewing techniques at different times of the day to see how you feel.  Don’t be surprised if you get the feeling of chaqi yourself.

40 Responses to “What’s the Real Deal with Caffeine in Tea?”

  1. Charlotte

    I’ve noticed that some teas make me feel more focused, while others make me feel more hyped up and almost jittery, and others yet make me feel sleepy. I’ve also noticed that most times I brew Gong Fu that I really feel like I could use a nap afterwards; while brewing in bigger mugs and pots give me the more alert to jittery feeling. Thank you for making me realize it’s not all in my head!

    • Ash-Lee (DaisyChubb)

      Of course it’s entirely dependent on the tea type, but more often than not I do feel more relaxed from brewing Gong Fu style as well! Although I often feel a calming sense of alertness instead of sleepiness, I know if I went for a nap it would come very easily haha.

      This is definitely a case of needing to keep a tea journal close at hand to see what teas affect me in what way – I think I’ll make that my late birthday resolution 🙂

      • Charlotte

        That’s an interesting idea. I keep a tea journal for all the teas I try, but I’ve never written down any symptoms I’ve had from the teas. I’ll have to start doing that now!

  2. I like your take on this! I get so worried lately when I see an article on caffeine from a tea company, because all too often they’re full of misinformation (white tea has less than green, a 30s steep will decaffeinate, etc.) but you really get to the heart of the matter here: how much caffeine is in the leaf or the liquid doesn’t matter nearly as much as how you feel after drinking it!

    • Thanks Olivia! I don’t get why tea companies make assertions about caffeine without reading any medical studies at all. When you really look at the good work scientists are doing, you can piece together a picture of tea’s physiological effects that is pretty interesting.

  3. kit_tea_cat

    Thank you for linking the actual studies referenced, that’s a rare thing and should be done more by sites that discuss tea and health!
    I appreciate your thoughtfulness and enjoyed reading the article.

    • I agree. The information may be out of my field I can interpret the relevance of the summations the various commenters have made – even just based on the effort to cite their sources.
      I know some friends who will react more positively to this support for more tea drinking or supplement taking than the social interaction aspect; as long as it sparks discussion and debate, it’s a start.

  4. Great article! Love that you’re addressing this. Curious though, in all my research (mind you, internet based) I’ve always seen green teas, particularly Longjing & Gyokuro, as having the higher theanine content. I’ve made it a point to seek them out. Curious to know more about fermented teas having more theanine.

    Here are a few links:

    But the these articles site black tea:

    And this article contradicts itself:

    And finally here’s a fairly level headed response to the question of which tea has the highest quantity of theanine:

    • Thanks Mark!
      I am going to take a look at all the great links you have shared. I didn’t get a chance to research the specific tea-by-tea L-theanine content as thoroughly as the general effects, so I am going to see what studies make the most sense and revise my article to reflect the complexity of the situation.

      My general sense is that if you really measured all tea out there, instead of category representation, you would find a lot of overlap among tea types in L-theanine levels. Is it that Gyokuro, Anji White Tea, and Longjing contain more L-theanine, or is it that the samples tested were higher quality, because only higher quality versions are produced on these teas for economic reasons? Very interesting to consider. I will post again when I take a look at the evidence.

  5. OMG! Tea and neuroscience! My life is complete. Excellent article, and some wonderful research, sir! I just wanted to comment on a few things I found in my review of some of the literature you cited.

    You cite that the Foxe et al. study from this year found increased alpha-band activity and decreased error rate in only the caffeine + L-theanine experimental condition. I’d like to add accuracy and point out that while this combined condition resulted in significantly reduced omission and commission errors, it was not significantly different than the caffeine-only condition, and it was similar to the reduced error rates found in the theanine-only condition. Essentially, all conditions besides the placebo resulted in participants making a similar percent of fewer errors. However, only when caffeine was given by itself did participants have significantly different alpha-band activity. There were actually no effects on alpha-band oscillations in any condition in which theanine was involved (Foxe et al., 2012: page 2326).

    Also, most other studies investigating the effects of theanine or theanine + caffeine involve the use of higher-than-average levels of theanine (as compared to a cup of tea). Actually, the other studies Foxe et al. cite (i.e. Gomez- Ramirez et al., 2007 and Rogers et al., 2008) both use concentrations twice as high as the levels Foxe et al. use (100 mg vs. 250 and 200 mg).

    This more recent study went with the idea that it seemed to be possible that when concentrations are lowered (100 mg theanine to 50 mg caffeine), there are additive effects that are not seen from either chemical on its own both behaviorally and electrophysiologically (e.g. Owen et al., 2008; Kelly et al., 2008). Yet, when using similar concentrations and methods, the researchers were unable to attain the same results.

    So, even when theanine to caffeine ratios are increased to 5-to-1, there still does not appear to be a difference in levels of sustained cognitive attentiveness compared to those derivative of caffeine alone. It may be that additional effects are not seen due to what Foxe et al. surmise as a possible “ceiling effect,” hence capping off all potential increases in attentiveness.

    This effect may also be present in the Griesbrecht et al. study from 2010 you cite. This study used similar techniques as Foxe et al., but did not include controls of only caffeine or only theanine. In addition, the researchers administered much higher than normal concentrations of theanine (again, compared to one cup of tea).

    I think the most interesting aspect of the theanine compound is its ability to mimic effects of caffeine without affecting reaction time (which seems to be consistent across studies) or alpha-band oscillations (at least according to the most recent literature). Since alpha waves are associated with selective attention and activity within the parietal and occipital lobes, but yet the theanine condition’s alpha fluctuations appeared the same as the control’s, it may indicate that theanine possibly influences attentiveness via processes outside of these brain regions. Perhaps, for example, effects are more salient in the frontal lobe? However, due to the conflicting conclusions in the literature, exactly how theanine helps improve cognitive attention capabilities and in what way alpha wave oscillations are affected is difficult to conclude at the moment. I’ll be very interested to see what the effects of closer-to-normal concentrations of theanine will be on vigilence and attention in future research.

    Kanarek et al. (2011) found fascinating support for theanine reducing stress and mitigating global processing biases naturally occurring from caffeine. Apparently caffeine can cause one to pay more attention to the larger picture, while ignoring smaller details. Yet, when theanine is introduced in addition to caffeine, this bias is reduced. So perhaps this could help explain how one can become more energetic and attentive after consuming tea, while still being able to focus more on in-depth aspects of an issue.

    I can’t find a full article, but this is a link to the abstract of that Kanarek study if anyone is interested:

    • Dear Cody,
      This is an incredible contribution you have made. I am so grateful for your time in helping to clarify some of the studies that I have examined. I have a real armchair interest in molecular biology, but these subjects are certainly outside of my field, so it is great to have such a thoughtful response.

      The Kanarek study is great support for the passing mention in the other study I cited of lower reported fatigue levels while performing tasks (regardless of error rates). I am going to look it over, and revise this article to reflect the insight that you have offered. I am really interested in providing an article on caffeine in tea without all the hearsay that is spread around these days.

      I will post a reply again when I am able to edit the article.
      Best Wishes,

      • Hi David,
        So glad I could help! I think this is a fantastic literature review that you’ve posted here, and I love that you took the time to find the most recent primary studies on the subjects instead of regurgitating old, outdated reviews of studies. I’ve been helping with research at my university concerning EEG patterns and responses to high/low action verbs, so the alpha-band study really caught my interest. If I happen on any other interesting articles concerning tea-related chemicals and their effects, I’ll pass it along to you!

    • Charlotte

      I have never found that one to be calming. That’s one that I drink when I want to wake up! Perhaps it’s a psychological thing though, I have no idea what the contents are of Yerba Mate.

  6. excellent article. along with calm and alertness, it seems that ‘freshness’ is another main characteristic of the experience that is evoked from a good cup of tea. Freshness is perhaps closely related to antioxidants. anti-oxidant rich foods tend to elicit a fresh feeling, and greener, more antioxidant rich teas often provide a strong fresh feeling. such as the laoshan green.

  7. Jesse Turits

    There’s such little real knowledge being shared about the beautiful and complex benefits tea has to offer. Sure everyone knows that green tea has antioxidants, but so do the others! Tea really is a wonder. This article is so important and inspires me to find out even more. I’ve been quoting it to all of my friends 😉

  8. LC Aponte-Blizzard

    I always end the day with a nice green tea brewed up gong fu. The ritual and the tea itself is so soothing that by the end of it I’m ready to go to sleep. I couldn’t possibly imagine ending the day without my “sleep ritual” now. 🙂

  9. Totally agree with this from personal experience. I haven’t had coffee in 7+ weeks, but instead 4-5 cups of tea (mostly black) a day. But yet the difference is undeniable. I think this article really hits the nail on the head by relating coffee vs. tea to quality of sleep. Its not the coffee that made me a nervous wreck necessarily, but the lack of quality sleep the coffee was causing. Thanks for sharing the research! This is something I’ve thought inside for a while but its nice to see some evidence that there is a difference between tea and coffee 🙂

  10. Great article, David. I’m a coffee drinker and roast my own beans at home. It’s more about the process from green bean, to roasted bean, to being ground up, and brewed. It is relaxing for me and I get a strong sense of alertness, happiness, and fulfillment from the resulting cup. That said, I only drink a cup of coffee a day and sometimes I pass on that cup all together. It depends on my mood. Tea has really taken hold throughout my day – I enjoy taking a break while at work to brew up some green tea improv Gong Fu style (small mason jar as gaiwan/strainer/small tea cup) and love it’s impact on me. Over the course of multiple steepings I find a strong sense of calm alertness.

    Tea has been a great companion to my mindfulness meditation!

  11. Joely (Azzrian) Smith

    WOAH! Not only a WONDERFUL and through article here but even the follow up comments have a heap of info as well.
    Much to read and much to study! Thank you David and everyone who has posted follow up comments with helpful links, and information. Its wonderful we can all learn from each other.

  12. Michelle

    Thanks for all the links to the studies! I can’t help but wonder if the reason that people can react differently to the same tea is the same reason that they react differently to different anxiety/depression meds or just have different moods in general, if there is this type of relationship between tea and things that can play with your neurotransmitters. I really wish I knew more about this

  13. This is an excellent article! I love the citations to relevant sources, and it is very well written. This makes me optimistic about caffeine, as last year I was having trouble with my stomach due to it. It’s nice to hear that I should actually be seeing how different tea varieties affect me, rather than just basing my choices on caffeine content alone. Thank you for your insight!

  14. Jim Hersh

    Is it true that it is possible to remove most of the caffiene from tea by doing a first infusion for thirty seconds and throwing out the tea, then using the leaves for a second infusion to drink?

  15. it’s always interesting to get into the discussion of caffeine content in teas, it seems there is never really consistent answers. this article was super interesting though, I hadn’t heard much about that other compound!

  16. Donna Benrmhardt

    any ideal where i can get the reql deal info on ” yaupon” i have lots of it growing and let me tell you its loaded with ccaffeine. i would like to mix it with something it and sell it.

  17. Cynthia

    We are such unique creatures, thank goodness! Three cups of delicious Qingming Long Jing landed me in the hospital with a coronary vasospasm. I just skirted a heart attack.

    So, go easy and do keep a tea journal of your experiences. Obviously, we all react to different teas, well… differently.

    A source of wisdom that brought me back to tea (one of my deepest pleasures and hard to walk away from entirely) is the Tea School on the site of Camellia Sinensis, an amazing tea house in Montreal. Check out the antioxidant and caffeine findings they amassed after a scientific study of their own teas. It led me to my two safe teas, their Kukicha and Verdant’s Autumn Anxi Tieguanyin. I’m not missing anything!

    • Lily Duckler

      Hi Darvin,

      Adding milk will only dilute the tea; it will not decaffeinate the cup of tea. That means that a single sip of tea will technically have less caffeine than a single sip of tea without milk. However, if you finish the whole pot of tea, you will consume the same amount of caffeine you would have consumed if you had not added any milk.

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