Tea contains 4 substances that have stimulating effects on your brain.

The best known is caffeine, a potent stimulant that you can also get from coffee, soft drinks, and energy drinks.

Tea also contains two substances related to caffeine: theobromine and theophylline.

Finally, it provides a rather unique amino acid called L-theanine, which has some very interesting effects on the brain.

This article discusses these 4 stimulants in tea.

Tea and coffee provide a different buzz

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The other day, I was talking with a friend of mine about the psychoactive effects of coffee and tea.

Both contain caffeine and therefore have a stimulant-like effect on the brain, but we agreed that the nature of these effects is quite different.

My friend used an interesting analogy: The effect provided by tea is like being gently encouraged to do something by a loving grandmother, while coffee is like being kicked in the butt by a military officer.

Since our conversation, I’ve been doing some reading on tea and how it affects the mind.

Don’t get me wrong — I do love coffee, and I believe it to be healthy. In fact, I tend to call it my all-time favorite health drink.

However, coffee does definitely have a downside for me.

While it tends to give me a nice and strong energy boost, I believe it sometimes prevents me from getting much done because the “wired” feeling can cause my mind to wander.

This excessive stimulant effect of coffee can make me spend a lot of time on unproductive tasks like checking emails, scrolling through Facebook, reading pointless news stories, etc.

It turns out that tea has less caffeine than coffee, but it also contains three other stimulant substances that may provide some sort of synergistic effect.


Coffee provides a stronger boost and greater stimulating effects than tea. It can even be so powerful that it may affect your productivity. Depending on the dose of caffeine and how rested you are, caffeine will generally improve attention.

Caffeine — the world’s most widely used psychoactive substance

Caffeine is the world’s most widely used psychoactive substance (1).

That sounds like a bad thing, but it doesn’t have to be.

Coffee, the biggest source of caffeine, also happens to be one of the biggest sources of antioxidants in the Western diet, and consuming it has been associated with various health benefits.

Tea is a moderate source of caffeine that is consumed worldwide, depending on the type.

Caffeine stimulates the central nervous system, increases vigilance, and reduces drowsiness.

There are several theories about how it works. The main one is that it may block an inhibitory neurotransmitter called adenosine at certain synapses in the brain, leading to a net stimulant effect.

Adenosine is believed to increase in the brain throughout the day, building up a kind of “sleep pressure.” The more adenosine, the greater the tendency to fall asleep. Caffeine partly reverses this effect (2).

The main difference between the caffeine in coffee and in tea is that tea has a lot less of it. A 5 oz. cup of coffee can provide 90–150 mg of caffeine, while the same sized cup of tea may provide 20–50 mg (1).

Keep in mind that 5 oz. is the size of your grandmother’s coffee or tea set, while most of us are drinking out of coffee mugs that may hold 15 oz. or 3 times the caffeine content stated here.


Caffeine blocks adenosine in the brain, an inhibitory neurotransmitter that promotes sleepiness. Tea contains much less caffeine than coffee, thereby providing a less potent stimulating effect.

Theophylline and theobromine

Theophylline and theobromine are both related to caffeine and belong to a class of organic compounds called xanthines.

They both have several physiological effects on the body.

Theophylline relaxes smooth muscles in the airway, making breathing easier while also stimulating both the rate and force of heart contractions.

Theobromine can also stimulate the heart, but it does have a mild diuretic effect and improves blood flow around the body, leading to a net reduction in blood pressure.

Cocoa beans are also good sources of these two substances (3).

The amounts of these substances in a cup of tea are very small, though, so their net effect on the body is probably negligible.

Some of the caffeine you ingest is metabolized into theophylline and theobromine, so every time you consume caffeine, you will indirectly increase your levels of these two caffeine metabolites.


Theophylline and theobromine are organic compounds related to caffeine and found in small amounts in tea. They stimulate the body in several ways.

L-theanine — a psychoactive amino acid with unique properties

The last substance is by far the most interesting of the four.

It is a unique type of amino acid called L-theanine. It is mainly found in the tea plant (Camellia sinensis).

Like caffeine, theophylline, and theobromine, it can enter the brain by crossing the blood-brain barrier.

In humans, L-theanine increases the formation of brain waves called alpha waves, which are associated with alert relaxation. This is perhaps the main reason for the different, milder buzz that tea generates (4).

L-theanine may affect neurotransmitters in the brain, such as GABA and dopamine (5).

Some studies have suggested that L-theanine, especially when combined with caffeine, can improve attention and brain function (6, 7).


Tea contains an amino acid called L-theanine, which increases the production of alpha waves in the brain. L-theanine, in combination with caffeine, may improve brain function.

The bottom line

Tea may be a suitable alternative for those who are sensitive to the higher amounts of caffeine in coffee.

Due to the presence of L-theanine and its effect on alpha waves in the brain, tea may also be a better choice than coffee for those who need to concentrate for long periods.

I personally feel pretty good when I drink tea (green tea, in my case). I feel relaxed and focused and don’t get the excessively wired feeling that coffee tends to give me.

However, I don’t get the same strong motivating effects of coffee — the mental kick I get after drinking a strong cup.

All in all, I believe that both tea and coffee have their pros and cons.

For me, tea looks like the better choice when doing work on the computer or studying, while coffee is better suited for physical activities like working out.

For others with jobs that interrupt sleep or tend to be monotonous such as first responders or nighttime security details, higher doses of caffeine may help improve reaction time, attention and focus.