The story of how I changed my morning coffee to green tea and how it changed my afternoon—why is it so different even though the caffeine is the same?

We didn't originally have a teapot for brewing tea at home.

One day, my wife asked, "I want to go to the 100-yen shop, can we stop by on your way home?" When I asked what she was looking for, she said she wanted to look at teapots.

It seems she had received some tea leaves from her mother.

We looked at the tableware section and found some teapots; there were two of them... both with designs that made it hard to choose.

Since they weren't expensive, I wanted us to buy one that we both liked.

In the end, we went to Nitori and bought one.

I didn't have a habit of brewing and drinking green tea at home,

"My morning doesn't start without coffee."

There was a time when I thought that way too.

One day, I just happened to pick it up, put some tea leaves and hot water into the teapot, and drank some green tea.

Since then, my morning routine has quietly,
but surely, begun to change.

At first, I thought, "It's probably just my imagination,"

but before I knew it, the way I felt tired in the afternoon and how I slept at night were a little different than before.

Both coffee and green tea,
contain caffeine.

Yet, why does it feel so different?

I got curious and looked it up,
and the answer was so interesting that I felt it would be of interest to those who make strength training or exercise a habit, as well as those struggling with work, housework, and childcare.

It started with a slight sense of discomfort regarding fatigue.

To be honest, I wasn't planning on quitting coffee.

It's just that for a while,
I had been feeling a sense of "sudden fatigue hitting me around 2:00 to 3:00 PM."

Even when I tried to focus on work,
my head felt heavy for some reason.
I would get sleepy in the evening,
and then couldn't sleep at night,
a vicious cycle.

At first, I thought it might be a lack of sleep.

But when I looked back on it,
I realized that the cycle occurred "a few hours after drinking my morning coffee."

I felt that the crash was particularly severe on days when I drank a lot of coffee.
Thinking, "Could it be the effect of the caffeine?" I decided to try replacing my morning coffee with green tea for just one week.

For the first two days, honestly, it felt unsatisfying.

"I feel like coffee wakes me up more."

"Isn't green tea a bit weak?"
That's what I was thinking.

But around the third day, something started to change. I felt that my concentration in the morning was lasting longer in a somewhat calmer way.

Even though they are both "caffeinated beverages," why are they different?

Both coffee and green tea are
drinks that contain caffeine.

However, the physical sensation when drinking them is clearly different.

To understand the reason,
I first organized the basic differences between the two.

Coffee (1 cup)

• Caffeine: 80–120mg

• Time to alertness: 15–30 minutes

• Duration of effect: 4–6 hours

• Theanine: Almost none

• Sudden and strong onset

Green tea (1 cup)

• Caffeine: 30–50mg

• Time to alertness: 20–40 minutes

• Duration of effect: 3–5 hours

• Theanine: Richly contained

• Gentle and gradual persistence

Looking only at the numbers,
coffee is the "stronger" drink because it has more caffeine.

But the issue isn't just the amount.
A component in green tea called "theanine" was creating the biggest difference from coffee.
the biggest difference from coffee.

Theanine changes the quality of caffeine

I used to think caffeine was just caffeine.

Theanine (L-theanine) is a type of amino acid found in abundance in tea leaves.
It is said to increase
"alpha waves" in the brain, which induce a state of relaxation, while simultaneously being involved in the regulation of dopamine and serotonin.

What is noteworthy is that it brings about relaxation
without causing drowsiness.

When combined with caffeine,
its effect becomes even more unique.

Caffeine alone vs. Theanine + Caffeine

Coffee caffeine suppresses drowsiness and promotes alertness by
blocking "adenosine receptors" in the brain.

This itself is the same for green tea caffeine.

However, in the case of green tea,
because theanine works at the same time,

it is said that it works to soften the "jitteriness" and "tension" of caffeine
while only enhancing concentration.
To use an analogy,

coffee caffeine feels like
"revving an engine suddenly."

Green tea caffeine + theanine feels like
"stepping on the accelerator while the suspension absorbs the shocks from the road surface at the same time."

You gain speed, but the ride is completely different.

This "gentle alertness" might be the reason why I felt it was easier to maintain concentration in the morning after I started drinking green tea...
as I researched it, it all started to make sense.

The true nature of the afternoon crash

That "sudden afternoon fatigue" I used to feel
when I was drinking coffee.

This is a phenomenon commonly known ascaffeine crash. Coffee caffeine reaches its peak blood concentration about 30 minutes after consumption,

bringing about a sudden sense of alertness.

However, after that,
adenosine returns as if rebounding, and drowsiness and fatigue rush in all at once.

This is considered one of the main causes of the "2 PM wall."

On the other hand,
green tea contains less caffeine,
and because the absorption is gentle due to the action of theanine,
a sudden peak of alertness is less likely to occur.

Consequently, the crash is also milder.

The first impression that "it doesn't feel as effective as coffee"
might actually be due to this "lack of a sudden rise."

Rest and relaxation—this might be what changed the most

The most surprising thing about switching to green tea in the morning was
the feeling that the quality of my sleep at night had changed.

Back when I drank coffee often,
my head would feel strangely active even at night,
and there were nights when I couldn't fall asleep even after getting into bed.
Perhaps those one or two cups in the morning were lingering until the evening.

Since switching to green tea,
my total caffeine intake has naturally decreased.
In addition, there is talk that the theanine in green tea 'may relieve pre-sleep tension and improve sleep quality.'
(Though this refers to drinking it before bed, it seems that for some people, drinking green tea in the morning can also indirectly regulate their sleep rhythm.)

Things I noticed after trying it for a week.
I feel like the time it takes to fall asleep after getting into bed at night has shortened.

'Trying to sleep but unable to'
that frustration has faded a little.
It might be close to the feeling of being able to fall asleep instantly even though my body is tired but my head is still alert.

I rethought what it means to relax

When you hear 'relaxing drink',
you might imagine herbal tea or chamomile.

But the interesting thing about green tea is that
it achieves the paradox of being able to concentrate while relaxing at the same time.
This is close to what is called a

'calm state of alertness' due to theanine, or in other words, a state of 'concentrating while relaxing.'

It is said that one of the reasons Zen monks valued tea lies here.

While alpha waves, which are close to a meditative state, increase,
drowsiness does not come.

Tea may have been the very drink that creates that state.

If asked, 'So should I switch to green tea?'

Having read this far,
some of you might have thought, 'I'll switch everything to green tea!'

But honestly,
I haven't 'quit coffee' myself; I just 'switched to green tea only in the morning.'

Coffee is by no means bad.
Its deep aroma,
the satisfaction when drinking it,
the feeling of a mood shift

There are certainly merits that only coffee has.
I believe the important thing is 'using them differently to suit your own body's rhythm.'

The 'different usage' I tried

Morning (after waking up until 9 AM) → Green tea
Coffee on an empty stomach is too stimulating. Green tea is less of a burden on the stomach and allows for a gentler awakening.

Morning concentration time → Green tea or 1 cup of coffee
On days with important work, use coffee for sharp concentration. On other days, take it slow with green tea.

Afternoon → Green tea or water
To avoid a caffeine crash,
I try to limit caffeine in the afternoon as much as possible.
Even with green tea, I keep it to a small amount after 2 PM.

If you feel like 'I've been easily tired lately,' 'I can't maintain concentration in the afternoon,' or 'I can't sleep well at night,' please try switching your morning coffee to green tea just once, for just one week. Whether you feel a difference depends on the person. But I felt it was 'worth checking' after trying it with my own body.

Conclusion

"Changing my morning coffee to green tea"

I never expected to feel changes in my body from just this.
It is not a dramatic change, but a small, quiet,
feeling that something is definitely changing.

It is difficult to make major changes to your health or lifestyle habits.

But if it is just "changing your morning cup,"
you can try it starting today.

A cup of green tea in your favorite teacup
might just change your afternoon a little bit.

If anyone else has tried this, please let me know in the comments.
I think the experience is different for everyone, so I would love to hear various opinions.