Does green tea keep you awake?

In this brief guide, we are going to answer the question “does green tea keep you awake” with an in-depth analysis of whether or not green tea keeps you awake. Moreover, we are going to discuss the effect of caffeine on the body and the way to properly store green tea.

Green tea, which accounts for 20% of the total tea consumption worldwide, is the primary beverage consumed in Asian countries. In Japan, 53% of adults consume green tea on a daily basis, and in China, 46.1% of adults regularly drink tea (1).

So without much ado, let’s dive in and figure out more about it.

Does green tea keep you awake?

So green tea contains 30-60 grams of caffeine per cup (2). It is approximately 3 times less than that of the caffeine content of coffee, which contains, on average 100 mg per cup, but still, it is caffeine and it will do what it is best at. 

So what caffeine does is that as soon as you drink a cup of green tea and the caffeine finds its way to your bloodstream, it reaches the brain and its effects on the brain include a general increase in neurotransmitter activity by blocking the inhibitory action of adenosine, a neuromodulator (3). Now when caffeine has bound with the adenosine receptors, the adenosine won’t find the receptors to attach to, thus it won’t be able to carry out its function.

Now the question arises “What is the function of adenosine?” and “How blocking adenosine activity is related to alertness and attention?” Adenosine is the neuromodulator that regulates the sleep cycle and also has an impact on the level of alertness and attention. So what adenosine does is that as soon as it gets attached to its receptor, it sends the signal to the brain that now it’s time to sleep. It induces sleepiness by sending signals to your brain.

Adenosine is reported to promote sleep by acting through A1 or A2A receptors, but the relative contribution of these receptors to sleep induction remains controversial (4).

Now in the scenario, where caffeine has blocked all the adenosine receptors, so when adenosine won’t be able to bind with its receptor, it won’t be able to carry out its function, thereby you will stay awake.

But here is a catch to this whole phenomena, there is another compound “theanine” present in the formulation of the green tea. Now what this compound does is that it works as the antagonist of the effect of caffeine, which means that it counteracts the action of the caffeine.

L-theanine is an amino acid found almost exclusively in tea. It constitutes between 1 and 2% of the dry weight of tea, which results in around 25-60 mg per 200 ml serving of liquid tea. It is thought to influence the central nervous system (CNS) through a variety of mechanisms (4).

Now the question arises “does theanine cancel the effect of the caffeine?” The answer to this is “No”. Especially the people who are caffeine sensitive won’t be able to sleep after drinking green tea. So it is recommended to drink green tea at least 2 hours before going to bed because if you consume the green tea at bedtime, it will hinder your ability to fall asleep. 

Moreover what you can try is to opt for a low-caffeinated green tea or you can steep the green tea at room temperature so that your brewed green tea will have low caffeine content (the higher the temperature of the water is more will be the amount of tea extracted and the more will be its caffeine content). 

Theanine may interact with caffeine because L-theanine has been found to decrease serotonin levels that have been artificially elevated by caffeine. Furthermore, L-theanine appears to antagonize the stimulatory effects of caffeine, which may contribute to its effects on lowering blood pressure and unlike caffeine, there is evidence that L-theanine could be associated with relaxation. However, there is evidence that L-theanine significantly interacted with caffeine in that it enhanced the effects of caffeine on simple reaction time, the accuracy of rapid information processing, mental fatigue, and tiredness when given in combination. Also, the combination of L-theanine and caffeine significantly enhanced the speed of rapid information processing, sentence verification, and word recognition reaction (4).

You can read about the benefits and risks of green tea here.

Other FAQs about Tea which you may be interested in.

Does green tea help with a sore throat?

Can you use a teabag twice?

What are the effects of caffeine on the body?

Caffeine increases the cortisol and adrenaline secretion in the body that results in increased heart rate, breathing rate, and mental alertness. It also helps you to focus and stay awake by stimulating your nervous system. Moreover, the coffee also contains dopamine that is a brain stimulator, and helps you to stay focused and alert (3).

The caffeine once consumed, starts working very quickly as it can easily pass the epithelial layer lining the mouth, throat, and stomach to reach the blood. So it takes about 30-60 minutes for the caffeine to reach its peak level and provide you with a surge of energy. 

Caffeine has a half-life of about 5 hours in an average adult body according to the FDA. This means that half of the caffeine, as well as half of its effect, is gone within the first 5 hours.

As the excessive intake of tea or coffee can increase your overall caffeine intake that can cause some health problems like bloating, gas, etc., therefore, it is recommended to limit your daily caffeine intake to 300 mg. Excessive consumption of caffeine from green tea may also cause central nervous system stimulation such as dizziness, insomnia, tremors, restlessness, confusion, diuresis (i.e. increasing urine output), heart rate irregularities and psychomotor agitation (2).

How to properly store the green tea?

The proper way to store green tea is to keep it in an air-tight container, jar, or air-tight bag in a cool, dry, and dark place. It should be noted that the place should not be humid or else the humidity of the environment can decrease the shelf life of the green tea.

When green tea is exposed to moisture there are great chances of mold formation on it and it will go bad afterward. Moreover, it should also be stored away from direct sunlight. So a cool, dark corner of your pantry will be a good place to store your green tea. If stored in the freezer, the humidity should be kept below 60% (5).

It was reported that tea catechins are not stable during long-term storage. During 6 months’ storage of green tea bags in their original containers at room temperature in the dark, the average content of EGCG catechins decreased by one-third and ECG catechins decreased by half (5).

You should always seal the pouch after scooping out the green tea. Moreover, you should never use a wet spoon to scoop out the tea from the package or the container in which it is stored.

Conclusion

In this brief guide, we answered the question “does green tea keep you awake” with an in-depth analysis of whether or not the green tea keeps you awake. Moreover, we discussed the effect of caffeine on the body and the way to properly store the green tea.

Citations

1. Kim, Jiwon, and Jihye Kim. Green Tea, Coffee, and Caffeine Consumption Are Inversely Associated with Self-Report Lifetime Depression in the Korean Population. Nutrients, 2018, 10, 1201.
2. Nawab, Amber, and Najaf Farooq. Review on green tea constituents and its negative effects. Pharma Innov, 2015, 4, 21.
3. Bryan, Janet. Psychological effects of dietary components of tea: caffeine and L-theanine. Nutr rev, 2008, 66, 82-90.  
4. Lazarus, Michael, et al. Adenosine and sleep. Sleep-wake neurobiology and pharmacology 2017, 359-381.  
5. Kosińska, Agnieszka, and Wilfried Andlauer. Antioxidant capacity of tea: effect of processing and storage. Processing and impact on antioxidants in beverages. Academic Press, 2014. 109-120.